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A Traitorous Heart

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A noblewoman in the scandalous French court finds herself under the dangerous and watchful eye of the Parisian royalty when she falls in love with the handsome king who is betrothed to her former lover in this bisexual The Three Musketeers by way of Bridgerton and F.T. Lukens.

Paris, 1572. Seventeen-year-old Jacqueline “Jac” d’Argenson-Aunis is lady-in-waiting to her best friend and former lover, the French Princess Marguerite “Margot” de Valois, but she dreams of more. If Jac plays her cards right, one day, she’ll become a full member of the Societas Solis, a secret society of spies—just like her uncle and guardian, Viscount Gabriel d’Argenson-Aunis.

But it’s hard to think about her own ambitions while France is on the brink of war, and the only thing that might save the country is an alliance—a marriage between the Catholic Princess Margot and Henry, the awful son of the Huguenot queen. Who would be the perfect person to play matchmaker? Jac, of course.

Jac resents lying to her best friend almost as much as she resents the brazen and arrogant King Henry, but it’s her one chance to prove to the Societas Solis that she belongs among their ranks before her uncle can marry her off or worse. The more time Jac spends in the French Court’s clandestine corners, though, the more she starts to wonder if Henry is…not as terrible as she once believed. And the Societas Solis may not be what they seem.

Politics. Spies. Chaos in the French court. Perhaps even witchcraft? Everything’s more dangerous when love is involved.

461 pages, Kindle Edition

First published January 7, 2025

19 people are currently reading
1652 people want to read

About the author

Erin Cotter

3 books92 followers
Erin Cotter writes young adult fiction. Originally from Buffalo, New York, she currently calls Austin home. When not writing she spends time with her partner and pets, eating tacos, and searching for Golden-cheeked Warblers in the Texas Hill Country.

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Displaying 1 - 30 of 83 reviews
Profile Image for alexandra osborn.
133 reviews102 followers
May 21, 2025
4.5

When I first learned of this book’s coming-into-existence, the Reign-obsessed twelve year old in me was awakened with the passion of a thousand suns that still hasn’t been put out 24 hours after finishing (I’m due for a rewatch I fear). Let me just tell you this: it did not disappoint.

A Traitorous Heart is a historical fiction (heavy on the
“fiction”) novel that has overdosed on dark magic, specifically that of one infamous Italian sorcerer. It follows this chic named Jaqueline (she goes by Jac because she’s not fancy like the other girls) and is a lady in waiting to and *former lover* to the princess of france, Margot. Now, Margot’s a real tart and things have since broken off because Jac is a Lover girl yk but when you basically have to spend every day with the girl you used to secretly kiss in random shrubs and dark corners well…

Enter Henry, newly coronated king of Navarre (idk if this country is the historical or the fiction part) and member #3 of our lovely little love triangle. Like Margot, Henry is a bi icon (a bicon if you will) so he has that extra zestiness which Jac really likes. Unfortunately Margot is engaged to Henry so Jac is sort of but not really legally obligated to not pursuit him. Except Jac is actually part of a secret circle of French spies and she is ordered by her Oncle (no that’s not a typo) to make sure Henry seduces Margot and Margot, being the lesbian goddess that she is, magically falls in love with him and they live happily ever after, granting peace to the realm.

But alas, if only it was that simple. What Jac soon discovers is that some Parisian psycho has been robbing graves around the city. That’s not to mention the equally (if not more) psychotic behavior just down the hallway from Margot’s dead-husband-obsessed mom Catherine de Medici and her lap dog Cosimo who stands in the corner whispering things to himself like a teenage boy entering his emo phase. In order to prove to her Oncle that she’s independent and doesn’t need to be married off to some man who probably can’t even read or sword fight or whatever hobbies she entertains, she must prove herself by not investigating any of these things and instead seducing Henry (non romantically) into seducing Margot (romantically) and seducing Margot (non-romantically) into accepting Henry’s seduction (romantically). Well, this is no fun for Margot who, it turns out, is actually very good at romantically seducing super hot engaged people and not very good at non romantically seducing them, so that’s very good for us.

Overall, it was so so fun to read. I looooved the plot, from the fun romantic and friendship elements to the magic and mystery. The language was beautiful and it was decently paced as well (a few small problems). It really is one of those books you can pick up and probably read in one sitting if you have to time for it (of which there is none if you’re in ap english literature and have 6 assignments due on monday). The only issues I had were that it seemed to drag a bit at the end there. The last 70 pages coulve been much more condensed)
and some of the romance could’ve been slowed down to keep the tension for longer (my biggest pet peeve).

Anyway, if you’re still here, you obviously have an interest for royal french girls with secrets and an affinity for being kissed (by multiple people, on the same day) so please go read this.
Profile Image for Marieke (mariekes_mesmerizing_books).
719 reviews870 followers
October 17, 2024
Actual rating 3.5 stars rounded up to four.

I fell in love with the first part of this book. I smiled, kicked my feet, and wanted to read on and on and on. Jac is such a fun character, and I adored the interactions between her, Margot, and Henry. That smile on my face grew and grew and grew, and I was ready to hit that 5-star button fast—until I wasn’t.

It’s not that I didn’t like A Traitorous Heart anymore because I still did, but that rush of excitement waned a little. Jac and Henry lifted each other up, and I rooted for them so much, but I think the romance came a little too fast for me. I had wanted it to be a bit more of a slow burn. I did like the ending, though, so therefore I round up my 3.5-star rating up to four.

Thank you, Simon & Schuster and Edelweiss, for this ARC!

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Profile Image for Brend.
813 reviews1,740 followers
March 9, 2025
A warning to Historical Fiction lovers: do not read this if you were outraged by the dresses worn on Reign

This could’ve been set in a fictional kingdom; France just had fun little things to add to the story

Now, if you want something to fill the void left by the cancellation of My Lady Jane, pick it up immediately

There was a full cast acting out every chapter in my brain. Someone needs to give me a big budget to produce this. Does anyone have contact info for the CW????
Profile Image for Anna (annasbookstacks).
674 reviews366 followers
January 6, 2025
4.5 🌟 !! Omg this was so good. This book hooked me from the start and I finished in 2 sittings. French royals, court drama and politics, a love triangle, a little magic, dark secrets, and betrayals, you never know who you can trust in this book and you won’t want to look away. Also had great LGBTQ+ rep. The love triangle had me sweating and biting my nails!! Every loose thread in this plot somehow tied together in the end and I was on the edge of my seat the whole time. Fast paced, constantly entertaining, I loved the characters, plot, and setting. I connected to Jac so much always feeling like too much but also somehow never enough. Not knowing where we fit. And Henry??? The historical fiction French king of my dreams. This book was action packed and lowkey anxiety inducing. My jaw dropped more than once. Really had the best time with it!!
Profile Image for Cristina.
334 reviews188 followers
January 10, 2025
This book will find a great audience in fans of shows like CW’s Reign or Prime’s My Lady Jane. This is a historical fiction retelling of the events leading up to the St Bartholomew’s Day massacre in 1572 Paris. Many liberties are taken with the historical accuracy, and slight fantastical elements are introduced as well. Like these shows, our characters are given a younger more modern makeover. But with more queerness. There is a lot of melodrama, romance, and poor decision making.

This is on the longer side at 450 pages, and I think it could have been trimmed down. I found myself getting bored around the 350 mark because we took so long to reach the climax. If anything could have justified the length, it would have been a slow burn romance. Unfortunately, we got the opposite. There was simply no need for Jac and Henry to almost instantly fall in love. They kiss at like page 100. I wish their romance had been dragged out more to help balance the romance to plot ratio. However, I will say the romance was the highlight of this book as Jac and Henry were very adorable. A part of me does mourn the fact that this was not a poly romance as I thought it had the perfect setup for one. It’s a shame that it didn’t officially happen, even though at the end it kind of felt like it did? I don’t know if Cotter was forced to keep it monogamous or what, but it is strange how Jac, Margot, and Henry’s dynamic concluded.

I wish there was more actual spy work occurring. I love some great court intrigue and I found this book lacking despite the entire plot surrounding an alliance amongst growing political and religious tensions. This leaned more into a murder mystery set up, which is fine. But it didn’t really fulfill the spy plot line I was hoping for. I wanted to see Jac’s intelligence more than her fighting prowess. I also didn’t really care much for the mystical elementals of this book.

A small thing that irritated me was the constant use of betwixt instead of between. I understand it was used to give a more old age feel to the prose, but it just felt out a place considering no other major language changes were made. Especially since this takes place in France, they’re technically speaking French. I don’t know why we’re using old English.

Overall this was entertaining and had a cute romance. But I did feel like it was lacking in many parts and I wish that the focus had been placed on developing other aspects of the story.
Profile Image for shatterinseconds.
358 reviews10 followers
February 5, 2025
Flirty bisexual male characters are such kryptonite for me!!! When a book makes me fall in love with the love interest, that’s when it becomes an automatic 5 stars.

I can not begin to explain in enough detail how much I enjoyed this book. I didn’t know what to expect besides queer historical fiction and possibly a poly trio but the characters and story surprised me. I couldn’t put the book down and only had to keep stopping because the night would grow dangerously close to 2am with work in the morning.

Henry, omg Henry!!! Perfect romantic lead. I love when the guy becomes an utter simp for the person he loves. His boyish charms won me over just like they did Jac. Their banter was spot on.

Also, I was really pleased to see that almost every main character (save for the antagonists) was queer, including Jac’s uncle. The queer positivity between the characters made me happy (though I would have loved to see some trans rep too!)

I will say the story is vague on whether Jac ends up with both Henry and Margot or just Henry but either way, there’s definitely a permanent queer platonic relationship between the three of them.

I wish I could praise this book more but I am terrible at writing long positive reviews so just go read this, please.
Profile Image for Eden.
939 reviews261 followers
January 7, 2025
A Traitorous Heart has too many descriptions to be worth the read. And 4/5 of the descriptions are unneeded. They don't advance the character development or plot and instead put the reader to sleep.

Also, I do not think this book should be compared to The Three Musketeers in any way, shape, or form. It's historical fiction: yes. There's a secret society: yes. But those things do not make this comparable to TTM. I kept looking for cool fights or traitors or SOMETHING and those things did not come to fruition.

This book's one saving grace is the romance. It was sweet and swoony and a lot of fun. But a cute romance does not a good book make. I was extremely bored 90% of the time.

Thank you to the publisher and NetGalley for providing me with an e-arc in exchange for my honest review.
Profile Image for Nicole.
9 reviews2 followers
April 4, 2025
*2.5

I liked the parts about bisexual suffering, I did not like the zombie stuff.
This entire review has been hidden because of spoilers.
Profile Image for B.
137 reviews
March 13, 2025
3.75

It was so fun to read a book set in the 1500s I feel like we never see books set during this time thats not a fantasy.

I think this book would have done much better as a duology. It was pretty long to begin with and there were lots of twists and turns but I feel like we missed a lot of the relationship building between Henry and Jac. Seeing how strong and undying Henry’s love and loyalty to Jac was, I would’ve expected to see more of their relationship to understand that. Instead, I feel like we saw them become friends and then were immediately in love with little development. Splitting it into two books would’ve given the story more time to develop. Also, Henry’s character was at time unrealistically honorable because he seemed to not be capable of thinking rationally at ALL.

Either way, I thoroughly enjoyed myself reading this. It was really fun to explore this world and part of history I didn’t know. Now, I think a lot of my problems with this book may just be because I’ve outgrown the young adult genre.
Profile Image for KMart Vet.
1,553 reviews82 followers
March 10, 2025
A fun and engaging queer romp set against the backdrop of scandalous French court intrigue. Jac struggles to keep her head afloat as she navigates her ambitions in a world filled with spies, political chaos, and secret societies. And it has some pretty fun tropes.

Jac wrestles with feelings of inadequacy, identity, and matters of the heart. Her internal conflict is both relatable and compelling, and her budding relationship with King Henry—although it feels a tiny bit sudden because it happens mostly off page—manages to offer a glimpse of vulnerability. I would have liked a deeper connection that could have been explored more thoroughly.

Additionally, some of the supporting characters felt a little unrealistic. I do not want to spoil anything, but some of these characters made pretty bad decisions that hurt Jac and all was forgiven soon after. It felt unearned and I did not buy that this was a natural character growth rather than just motivated by the plot.

The pacing of the novel is a little odd: the beginning drags, so I thought this was going to be a slower, more political read. And the latter half shifts into a breakneck pace that feels more like a different book entirely. Despite these issues, the story remains a delightful escapade, rich with interesting family dynamics and political undertones, making it an enjoyable if somewhat uneven read.

Overall, a fun story with queer representation. Highly recommended for those who enjoy a playful yet dramatic tale. But I did not get Musketeers vibes at all.
Profile Image for USOM.
3,368 reviews297 followers
January 30, 2025
(Disclaimer: I received this book from the publisher. This has not impacted my review which is unbiased and honest.)

I will always read queer historical fiction stories. And A Traitorous Heart is a delight. I fell into Jac's story. She so desperately wants to be part of this secret society, but what if they're hiding more than she thinks? A Traitorous Heart is full of meet cutes, hidden relationships, and covert meetings. At the heart of A Traitorous Heart is this question about how do we fight for the future. We can think we have to do something, but what happens if we didn't? If we didn't manipulate our friends? If we didn't hide our love? Cotter balances our pursuit for love with saving the future of our kingdom.
Profile Image for Lucia.
496 reviews37 followers
Read
January 1, 2025
Thank you NetGalley for the eARC!
Profile Image for Kayleen.
387 reviews123 followers
December 17, 2024
4.5 simply because i can’t tell if it was a canon throuple by the end

this felt like the reign tv show but more historical accuracy and i mean that 100% as a compliment, i loved that show until francis died. and if you haven't seen reign, just go on pinterest and look at the mood boards and that is this book.

also erin cotter, if you see this, are margot, henry, and jac a throuple please i beg i need them to be
Profile Image for Farah ♡.
329 reviews52 followers
November 19, 2024
A historical fantasy YA with political intrigue? Always a YES.

This book captured my attention from the start, and I was hooked. I absolutely adore all the main characters. Jac and Margot were such a refreshing pair, and I can’t help but love Henry to bits. Seriously, we all deserve a Henry in our lives.

The court politics had me bracing for the worst possible outcomes, but the author navigated it all very well. The magic system and the plot were engaging, though I feel they could have been even more fleshed out. That said, I do appreciate how unique the story was—I haven’t come across anything quite like it before.

One of the standout aspects of this book is its diverse queer representation, not just among the main characters but also the side characters. I do wish there had been more exploration of these relationships beyond just a few mentions. Given the setting in the late 1500s, it could have added an interesting layer to the story.

The chemistry between all the main characters was chef’s kiss. I especially would have loved to see more of Jac and Margot’s romantic relationship, perhaps even through flashbacks before Margot’s focus shifted to Henry. But their friendship was still so heartwarming.

Now, Henry. Oh, Henry. He is the ultimate book boyfriend (or should I say book husband?). He was absolutely wonderful from start to finish.

And can we talk about the cover? I’ll definitely be buying a physical copy, because it’s just gorgeous. Huge props to the artist!

A big thank you to Simon & Schuster for the ARC 🫶 (Maybe you can send me a physical one too? 😉)

Profile Image for toby⋒.
396 reviews
Read
January 12, 2025
Dnf at 54%. I rlly wanted to make it through this book, but it’s just not for me. I think other people would like it, but personally the plot doesn’t move fast enough or progress much and the romance felt kinda rushed/sudden. I’m trying to train myself to dnf more books instead of forcing myself through them, so even though I really wanted to enjoy this book I’m not, so I’m going to go ahead and put a stop to reading it now. I’m not going to give it a lower star rating, because I think I’m maybe just not the target audience and I don’t want to negatively affect her overall rating! 🥲🥲
Profile Image for haley smith .
4 reviews1 follower
February 7, 2025
i actually liked this book a lot more than i thought i would given that i had never heard of it and picked it up literally only because i saw it was set in 16th century france. i loveddd the combination of history with fantasy and it was a fun little easy read and henry and jaqueline’s relationship was actually so cute, though i wish it was slower. the magic system and writing definitely could’ve been more descriptive but it was still a fun read :)
Profile Image for Samantha Refvik.
98 reviews
February 9, 2025
This was a pleasant surprise, I read it for a book club and enjoyed it way more than I expected to enjoy a YA historical romance/fantasy. Great characters and rep too :)
Profile Image for Ashley LeCates.
104 reviews
November 24, 2024
Thank you to NetGalley for the ARC.

If you liked the show Reign, this is definitely the book for you. Historical and fantasy and romance all wrapped up in a beautiful story. I enjoyed the addition of Jac to the story, but how it still managed to hit key historical points.

The magical part of the novel doesn’t come into play into the second half, so the beginning is mostly focused on the romance and female empowerment. Historically, Catherine De Medici was a strong Queen and regent, who firmly believed in the Valois line, Henry IV did become king of France (though this isn’t mentioned into the novel) and marries the youngest Valois princess, Marguerite. The St. Bartholomew Day massacre is also a key point in history and I enjoyed that the author was able to incorporate these significant points while not making the novel feel like a textbook.

The romance was good and not overpowering, and I appreciated the inclusion of LGBTQ characters. I think the author did a great job pulling everything together while being entertaining for a YA audience.
This entire review has been hidden because of spoilers.
Profile Image for Karis.
498 reviews31 followers
December 9, 2024
~~Thank you to Edelweiss and Simon & Schuster for the ARC!~~

2.5/5 stars rounded down.

I was enjoying this decently until magic came into the plot.

I did expect the characters to possibly consider magic as an explanation for what's happening, as it was the 1500s, and such explanations were much quicker to jump to than they would be today. But then the historical fiction swiftly slipped into historical fantasy about two-thirds way into the story when it was revealed that, yes, magic was real in this world.

I found this to be a very cheap twist. It didn't make the story more interesting; if anything, my interest immediately dampened. It made the story much more convoluted than it needed to be, and the fact it was introduced as a real element so late to the story really threw the world's rules out the window. We don't even get a proper explanation on how it works, only does it does. This annoyed me greatly, and it being the primary focus on that last third of the book kind of ruined the reading experience to me.

It is a shame, because I did find the story between Jac, the royals, and the secret society to be somewhat interesting. Jac is a deeply flawed protagonist whose trust and self-worth issues are tackled head on consistently throughout the book, and the dynamics between her, Henry, and Margot had some solid potential that I was really liking. This book would have been a solid three stars if the magic wasn't brought in.

Overall, it is in my opinion that the sudden inclusion magic does not make a story better. This story already leans heavily on the fiction aspect of historical fiction; adding magic on top of it was doing way too much.
Profile Image for Jes.
433 reviews26 followers
February 2, 2025
WHAT a delight. This had everything—adventure, suspense, betrayal, creepy dark magic, court intrigue, and of course, bisexuals with emotional baggage (is that not what we all read for??? lol just me?). So much fun and also I accidentally learned some French history along the way. Also everyone who is asking if the love triangle ended up in a throuple: of COURSE they did and it was PERFECT. Love that Margot was like I can & will roll with this. You just try leaving me out of this marriage.
This entire review has been hidden because of spoilers.
Profile Image for Hannah Delano.
189 reviews40 followers
March 24, 2025
This is young adult novel set in 1500s France prior to the St. Bartholomew's Day massacre. As a fan of shows like 𝘙𝘦𝘪𝘨𝘯 and 𝘔𝘺 𝘓𝘢𝘥𝘺 𝘑𝘢𝘯𝘦, I absolutely ate this story up!

This book is a mix of so many genres I love: historical fiction, romance, mystery, and a dash of fantasy. Jac is a French noblewoman (and member of a secret society of spies) that is tasked to help her best friend (and former lover) Princess Margot fall in love with King Henry. With a cast of queer characters, lots of banter, and a twisty ending, I really enjoyed this one.

🎧 Narrator: Gilli Messer
🎧 Length: 11 hours 45 minutes

This is my first time listening to narration by Gilli Messer and I loved how she brought the humor and wit of the characters to life. I’d highly recommend the audiobook format!

Thank you to Simon Teen and Simon & Schuster Audio for providing me with copies of this book. This review is voluntary, and all opinions expressed are my own.
Profile Image for Christina.
33 reviews1 follower
February 8, 2025
2.5 - take a shot every time you read the word “betwixt.”

I found it hard to read, mainly due to the MC being so naive and brash. I liked the concept but found some parts to not be believable or logical. Every chapter
Jac seemed to switch identities - from nobility to peasant - using them as a way to cast judgement on nobles or shame her mother for loving a peasant. I would’ve liked if every scene didn’t feel so rushed. It felt like a major event would take place but it was over within two pages and nothing bad actually happened.
This entire review has been hidden because of spoilers.
Profile Image for Showmia ୨ৎ xx.
41 reviews
February 16, 2025
4.75! ♡

Cruel prince vibes while set in Paris in the 1500s but make it a beautiful queer love story = chef's kiss!

This had so many elements of books I already love and combined them to make a truly unique and captivating story. Immersive reading is my bread and butter, so having the audiobook while reading it really brought this story to life, to a point where I felt like I was right there with them in the heart of the Parisian court. I loved the FMC, Jacqueline because she was the definition of a badass! She reminded me so much of Jude because she was still human but was also fighting for a place in society while constantly being told she will never be more than a wife. Her relationship with her uncle was so interesting and reminded me of Jude and Madoc's relationship, how complicated it was yet you could feel how much they cared for each other. He challenged her but also belittled her, dangling a future in front of her that he believed she couldn't attain. He was still proud of her but he struggled to show her that and hid behind his secrets which ultimately did fracture their relationship. But she only proved him wrong in the end.

All of the characters were complex, layered and flawed in their own ways. They all had so much weighing on their shoulders and that as a result affected their actions. I really liked Jacqueline and Margot's friendship, how they still had so much love and affection for each other despite their past. It was so sweet, heartwarming and a great representation of positive female friendships. Considering the difference between their statuses and place in society, the two girls had each others backs and was willing to go to the ends of the earth for each other. Margot was a formidable force to be reckoned with but she also showed so much vulnerability and humanness being a princess and a girl who wanted to do right by her people. Her friendship with Jacqueline really helped keep her grounded but also gave her the freedom to be entirely herself and fight for true happiness.

Jacqueline was head strong and loyal, but meeting Henry is where she truly realised that he was what her heart had been missing. Even though she had loved Margot, she struggled to open up and her heart towards her and many others. Because of her uncle's inability to show affection and constant lack of openness, she guarded her heart like a treasure and never let anyone fully get to hold it, in the fears that they would break it. She closed herself off from romance and love, and as the story progresses, we see her going on this journey of not only learning to be more open and less afraid of rejection, but also learning to let others in and be vulnerable with them.

Henry slowly but surely knocked down her walls, brick by brick until she was left completely raw and vulnerable, but she wasn't alone anymore. He was so down bad for her, yearning for her from across the room, constantly seeking her out in any place and reassuring her with his words that he would always be there. Even though she would turn him down and reject him countless times, he never faltered in his affections for her and would do anything to be with her. He had the weight of an entire nation on his shoulders, a future that had been written that he had no choice in and yet the only thing he truly ever wanted was her.

The tension and desire between them was palpable and my jaw was quite literally on the floor when they were first kissed. You could truly feel the passion and yearning they had for each other, how they could simply not stay away from each other despite all the stakes. The forbidden moments, the longing, the fact that there is a war looming over their heads and yet it was just the two of them in the world. He was willing to give up his entire kingdom for her and she was willing to let war and her uncle's secrets tear apart Paris because that is how much they loved each other! If that is not an earth shattering romance, I don't know what is!

A story that still sticks with me, characters and a world I long to be part of and have never forgotten. An incredible tale and one I am already itching to reread! Erin Cotter, you are magic and I will read everything else you have written! ✮⋆˙
11 reviews2 followers
January 10, 2025
A work of queer historical fiction, A Traitorous Heart follows scandal-born Jacqueline “Jac” d’Argenson-Aunis as she navigates the treacherous politics of the French court at a time when it seems that one wrong move could push France into war. As if that weren’t daunting enough, Jac yearns to join the Societas Solis, a secret society of spies that her uncle – the sole family member she has and the man who raised her – is part of. The Societas Solis is shrouded in mystery and secrecy, but Jac knows how to keep secrets, weave compelling lies founded on scraps of truth, and fight and wield weapons. Except that when her uncle finally relents and allows Jac to take a small part in Societas Solis work, her first mission is nothing like what she expected: she is to play royal matchmaker for her best friend and former lover, the princess of France, and the King of Navarre. With countries and hearts on the line, what could go wrong? (Spoiler: a lot.) What starts out as political matchmaking spirals and snowballs: assassins and murders, exhumations, impossible promises, improbable romance, betrayal, madness, and a dash of magic.

A Traitorous Heart brims with complex characters grappling with society’s expectations and their own desires. Jac, Henry, and Margo all have big, unruly emotions and complicated relationships with themselves, others, and their countries. (Jac’s relationship with her uncle stuck out to me in particular for its well thought-out complexity, nuance, and evolution.) These characters are real and messy, making mistakes, getting upset, doubting themselves, pushing themselves. Jac’s journey throughout the book is nothing short of transformative and revelatory: a lonely girl becomes a confident woman learning to put her trust in others and their unconditional love for her, instead of carrying her burdens alone and unacknowledged. Jac’s deep-seated need to prove herself is something that I – and I imagine many people, women in particular – relate to. I loved watching her acknowledge and accept her own self-worth (and be a skilled, accomplished badass who can take care of herself!).

Cotter’s beautiful writing abounds with gorgeous figurative language (including recurring imagery for specific characters that highlights and supports their arcs and relationship dynamics), laugh-out-loud witticisms, and heart-rending moments. The romance is only one part of the plot and doesn’t overwhelm the narrative. Rather, it compliments the non-romantic plot threads, adding to the story’s existing stakes and tension. On top of her deft storytelling, compelling characters, and nuanced plot, Cotter also does a small thing that I personally love when authors do: there is a line in the book which includes, and contextualizes, the title of A Traitorous Heart. It’s in the latter half of the book but well worth the wait!

A Traitorous Heart is a captivating, well-written take on historical fiction that I didn’t want to put down (while simultaneously not wanting it to end…). More than that, it is exactly the kind of book I wish I’d had growing up, and I’m grateful that it exists for people of all ages now. I simply adore it! Read it and discover Cotter’s brilliance! (And while you’re at it, grab her debut novel, By Any Other Name, too!)

Many heartfelt thanks to the author and the publisher for the eARC!
Profile Image for Terry.
105 reviews13 followers
December 16, 2025
What happens when love becomes all-consuming and destructive? A Traitorous Heart by Erin Cotter explores that question through court intrigue, secret societies, forbidden feelings, and an unhealthy hunger for power. A strong female protagonist ties it all together, though at times she seems less than adept at tying the laces.

The story is narrated by Jacqueline “Jac” d’Argenson-Aunis, a lady-in-waiting to Princess Marguerite “Margot” Valois, daughter of Catherine de Medici, in 1572 France. Raised by her uncle after her mother’s death in childbirth, Jac dreams of independence and of rising beyond her commoner’s birth. Those ambitions center on gaining entry to the highly secretive spy society known as Societas Solis, a goal that will cost her more than she anticipates, all while France teeters on the edge of religious war.

Cotter’s writing style is restrained, precise, and psychologically attuned, which makes it well suited to court intrigue. Her controlled sentences and carefully chosen metaphors allow tension to build between what is said and what is withheld. Prose that is highly observant of interpersonal dynamics mirrors the very setting she is writing about, a court full of gossip and secrets, where many wear two faces. She trusts her reader to read the room.

The main characters are well crafted, with clear strengths and vulnerabilities, as well as defined dreams and fears. Some of the more minor figures, such as Catherine de Medici, could have benefited from greater depth. The pacing felt off-kilter to me, seesawing between slow build and sudden bursts of action. The climax, in particular, seemed to arrive emotionally before it did narratively; it took too long to reach its peak, then rushed through its resolution. Jac does ultimately grow as a character, learning that love is fragile and must be handled with care in a world that is often unkind, though it felt like it took her ages to get there. She is, undeniably, a stubborn protagonist.

I enjoyed reading A Traitorous Heart, though there were several moments that required a level of suspended realism high enough to prompt a quiet chuckle. Perhaps I am simply too old and cynical, but certain events strained plausibility for a woman living in that century. Still, I appreciated what I took to be the novel’s overarching message. This is a good fit for older readers of the young adult genre, particularly given the book’s descriptive violence. Readers who enjoy historical fiction threaded with magical realism may also find much to admire here.

Nerd Rating: 🤓🤓🤓 — Smart, atmospheric court intrigue with thoughtful ideas and uneven execution.

Let’s discuss: Do you prefer stories that ask for emotional realism, or are you happy to suspend disbelief if the message lands?
Profile Image for Minh.
127 reviews
August 22, 2025
⭐️ 3.4 stars

This is actually not a bad read. I didn't expect to drawn in as much as I was. It's also mostly enjoyable aside from some slow parts.

I really liked all three main characters and they were my favourite part of the book. Jac is a great character and I enjoyed reading from her perspective. She's clever and funny and deeply passionate about creating peace instead of war, no matter how tempting it is for her own gain. Her attachment to her Oncle is recurring throughout the story with how she wants to impress him again and again even after what he did. The behaviour of her Oncle was honestly so disappointing. It never seemed like he tried protecting Jac enough and he was given endless chances just to disappoint over and over again. It was not until nearing the end did he finally did something but it was just not worth forgiving everything else. At least he seemed remorseful. Henry is such a fun character from the first page he was introduced. I do feel like he needed a bit more backstory but overall he brought every page to life by just being there. I did not initially like Margot but she appeared more later on and she definitely grew on me. She's similar to Jac but with a ton of attitude and boldness; very entertaining. She was there less than Henry was for Jac and they get an equal appearance later on but I would've liked a fair amount of page time for them both.

The romance was also a fun part of the story. While it was cute, it happened very quickly and I think it was rushed. Having it being slow burn would've been more compelling to my liking. Also, the ending to romance was not really explained. A throuple seemed fitting but I'm not exactly sure what happened.

The plot is confusing although initially seeming straightforward. It starts off slow and at about 150 pages in is when things pick up the pace. Then the story takes a full 360 spin with magic, crazying action, underlying secrets not even Jac knows of and some very quick and convenient solutions. The Societas Solis is not what it seems and while I do understand why it's secretive, they was almost no hints about what the group truly is until the nearing the reveal. Explanations were rushed and even I still don't really understand the purpose of why the members do what they did.

The pacing is totally off with an incredibly slow and lengthy beginning and then action scene after action scene after. I do think some scene cutting would've made things flow smoother. The book is not really long but it is unnecessarily lengthy and dragged sometimes.

The ending's not too bad. I think it wraps up things well. Some things are left a little open ended with the final chapter, but overall it was a pretty well deserved ending.
Profile Image for Frank Chillura (OhYouRead).
1,702 reviews77 followers
May 16, 2025
While I did not get the throuple I wanted outright, this still had the poly vibes I had been hoping for. I’m not spoiling anything by saying that, because it’s GIVING EVERYTHING on the cover, dahling!

Until recently, I hadn’t been the biggest lover of historical fiction, but I just think I didn’t know my preferences when it came to the genre. Just like all genres, I’m going to like some things more than others and I’m learning (albeit slowly) what I love. And whatever Erin put into this book is definitely what I love (and more).

The French court is historically the most scandalous (I don’t know if that’s exactly true, but I’m going with it based on my minuscule bit of knowledge based on television shows😝) and we find ourselves smack dab in the middle of it. Jac is a lady in waiting to her ex-girlfriend, the French Princess Margot. Where they were once making out behind the bushes, she is her confidante. So when the King of a smaller country, Henry of Huguenot, comes to ask for Margot’s hand in marriage and is immediately denied, it becomes Jac’s duty to help him woo her hand.

A lot happens that I don’t want to ruin that leads her to that point, including an almost marriage proposal for Jac to a character that is not important, but suffice it to say that to stay by her friend’s side, someone she loves, she has to help them wed. Even though Margot herself is only interested in women.

But what happens when Henry and Jac begin to have romantic feelings for each other? A whole lot of bi-panic and scrambling. Let’s just say that this so gay and I live for it!

In this version of fictionally semi-accurate history, we get a bunch of The Three Musketeers type action, some secret court espionage, and magic. (Cue the sparkles and dazzling eyes!!) Yes, this book has slight fantasy elements… more than slight, but it doesn’t come into effect until later on. Up until then, you think it’s all made up. That was spoilery-esque, but I don’t think it’ll ruin the experience.

This is the epitome of “I want two boyfriends and I want my boyfriends to be boyfriends,” but if the sexes were mixed up in the saying…. You get it! Well, you will once you read this!

Thank you to Simon Teen for sending me a finished copy of the book. I ended up reading the audiobook at the same time as the physical book and it heightened the experience. 👨🏻‍🍳🤌🏼💋
Profile Image for Robin Furlong.
5 reviews
February 7, 2025
Actual rating: 3.5

This book brought mixed emotions for me. I love the historically accurate details and using real people for the main characters (interesting choice by the author but it somehow was very cool) and the plot twists were satisfying and a wow-factor. Sometimes the romance and plot would be so good one moment, and then kind of “eh” the next. I absolutely LOVED Erin Cotter’s first book “By Any Other Name” and was a bit disappointed with her sophomore book.

Of course, the bad things were little things and the book was overall enjoyable. I understand how hard it is to write a good book and making sure it’s all well, so here are some things I loved!
The characters were lovable as always, but it did feel a little odd seeing them as characters when I found out they were real people. I thought that was very interesting though.
The overall plot was written very nicely! Plot twists never disappointed and were never out of the blue or seemed like the author ran out of ideas.
Great language and writing style that appealed to me nicely as well

There were however some things that I was cheering on so hard but was sad to see how they turned out. (I have full respect for this author, and still loved her book, just some details or missed opportunities).
There was one plot twist that I absolutely loved, but once it happened it wasn’t mentioned again or explained further (I won’t mention it for spoiler reasons, but it had to do with Jac’s Oncle and what he referred to her as in the cell). I really wanted to know the full story behind it!!
The romance was lovely, and leaned on very popular/common romance details which isn’t bad, I just prefer romance plots that are a bit more out of the box. Written very well for this type of romance though!
The ending was what I fret most over. Not the worst, of course, but when reading the Wiki pages for the character Henry I read a bit about his life. There were real life events that this author could have incorporated so wonderfully into the book (about Henry’s marriages) but perhaps she tried and simply could not.

Overall, a nice book that was not regrettable. Recommend if you enjoy romantasy, historical fiction and its great details, and spy/assassin plots.
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