The Prince's Vow

Runes of Pain and Peace #3

by Celeste Baxendell

A prince in need of a bride. The mage who has hated him all their lives. What lengths will he go to in order to win her love?

Commander Aimilia was born into war, but now that her nation has peace, Aimilia has nothing but a secret that would mean her death. She has no fiancé, no position, and an ailing grandfather. All she wants is to hide her treason, and secure her position and safety by winning her grandfather's title after his death.

But as Prince Nikias closes in on her, she’s certain his attention will only end in her execution. The last thing she expected was for her ex-fiancé’s older brother to ask her to be his bride. How could he ever think she’d want to marry him?

Nikias secured historic peace, but it came at a great cost. What he saw cannot be unseen, but he’s determined not to let the Seer’s future come to pass. The Seer has tormented him enough by taking his first love from him; he will not let her take his second.

He will marry, and there is only one woman he has in mind as his bride. But, in order to defy fate, Nikias must secure her love before making her his wife. New enemies rise from the shadows. As his past haunts him and his future condemns him, how can Nikias prove to her he’s not the villain he used to be?

Genres: Fantasy

621 pages, Kindle Edition

Published January 23, 2026

About the author

Celeste Baxendell has always read anything she could get her hands on, but once she read her first fantasy novel, she was hooked and hasn’t looked back since.

Her love of magic, adventure, and romance hasn’t waned with age, and she endeavors to write nail-biting stories with compelling, complex characters, and finding light in dark times.

She is incredibly blessed to spend her time writing from her favorite chair with her legs curled up under her as she fights the southern heat. When she isn’t writing, she’s either reading, drawing, or sewing, in that order, and most likely thinking about writing as she does.

Reviews

[✨Ruthie · Rating 5 out of 5]

⭐⭐⭐⭐⭐

🏛️⚔️🌿💔💞✨

I trusted this book.
Actually... that was my first mistake.

Yearning so thick you could carve it into marble 🏛️
Slow-burn looks, almosts, words left unsaid 💭💞
Then—betrayal. Sharp. Personal. RUDE. 🗡️💔

Every time I thought, okay, surely I'm gonna safe now —
❌ WRONG ❌ Like, WHY AM I SUPPOSED TO SURVIVE THIS!?!?!?
Another twist. Another reveal. Another emotional ambush.
⚡⚡⚡
This baby was CHUNKY! But, ohmygoshhhh, Nikias and Aimilia!!! Stopppppp 😭
Crazy well written. READY FOR BOOK 2!

I was gaslit by the plot. I loved every second.
Five stars. No peace.
🏛️🌿💔💞⚔️

Thank you to the author for this ARC!!<3

[Ashlyn Sanders · Rating 5 out of 5]

I don't have words. I am absolutely stunned at the magnificence of this book. I already was in love with the first two books, but this was on a whole other level. This book, following Amilia and Nikias, was a unique insight into both characters and their fate. I now have a new love for these characters and am just as obsessed with them as I am Marcella and Gavril. I can't wait until I know what happens next!
Thank you for letting me read an early copy of this book!

[Jessica · Rating 4 out of 5]

Prince Nikias has secured peace for his people, but it came at a high price. Commander Aimilia has a secret that might get her killed. When Nikias seeks Aimilia's attention she's convinced her secret is out, but instead she receives a marriage proposal. Shocked, she declines, because how could she ever marry someone she hates so much?

In the first two books of this series (with Gavril and Marcella as MC's) it was so easy to hate Nikias. He was a true villain who did unforgivable things, so I wasn’t sure my feelings for him was going to change. But I didn't have to worry; Baxendell managed to convert me! I was also anxious over Aimilia's feelings for Nikias.

"You are vicious, vengeful, and the cruelest man I have ever met. You're a liar. A manipulator. You don't listen to anyone but yourself."

She really despises him, so how is that going to change? But even this the author manages to make believable.

Nikias doesn't have an easy task trying to convince Aimilia that he's changed, and he makes it even harder by not revealing certain things. His actions at least makes Aimilia starting to view him differently, but every time she begins to "soften" something happens that makes her believe that he's manipulating her again. The frustration I feel! Both are also so stubborn that I want to shake them!

My mind gets blown several times and Baxendell gives me a real roller-coaster ride of emotions! Some things I find a bit repetitive, and considering the lenght of the book (over 600 pages) I believe it could have been shortened a bit. I also thought Aimilia and Nikias would get their happy ending here, but no, I'll have to wait desperately for the next book!

* I received an ARC from the author and I'm giving my honest review. *

[Orangetails · Rating 4 out of 5]

This is the book other novels should use a reference for lovers destined to never be together. Even when the world is pushing them to marry, there is always something standing in the way...usually, the other person's mistakes or assumptions about the other person. I am still not a huge fan of Nikias because of how he treated Marcela, but I do appreciate the redemption arc this book gives him. And it's clear that for all his flaws (and there are many), he loves with his whole heart. His utter devotion and loyalty to those he loves leaps off the page and is a personal inspiration to me.
Amilia also loves with her whole heart, but only most of the time, because Nikias has fallen short one too many times for her to be careless. She definitely comes into her own in this book; she's always been a force to be reckoned with, but seeing her point of view really highlights her strategic mind and depth of feelings towards others, which is not always shown externally.
The story is as good and twisty as the others in this series, with lots of twists and turns (plus adorable swoony moments). However, it's main theme is the romance, which is stellar. Whereas the theme with Marcela and Gavril was hope (or maybe faith), this one is agony. Nikias is in love with Amilia but can't tell her. Amilia is starting to fall for him but is tormented about it because of Nikias' mistakes. It's haunting and leaves you aching for them to be honest with each other, but even when they are, there's so much in the past that they just can't get on the same page. There's something always missing from the other person's point of view, and it's heartbreaking in the best way. There's some swoon amidst the heartache, though, and it's clean without being boring.
Overall, I think I liked it even better than its predecessors, shockingly. Amazing, amazing writing, as always!
(Oh, and I received this book in advance from the author, BUT I also purchased a copy of my own.)

[Patty Mooney · Rating 5 out of 5]

Oh man! I had hoped that Nikias and Aimilia's story would be just one book...but alas, I must wait to finish their story! Nikias and Aimilia are complex characters (just like Gavril and Marcella) and this book definitely dives deep into that complexity! I can't wait to finish their story!

[Jen · Rating 5 out of 5]

I have hated and loved Nikias since The Prince’s Captive. He was always a complex character and was a bit of an antihero in the first two books. He did some horrible things in the past. But his intentions were always to protect his brother even though his actions were terrible. Nikias redeemed himself in this story. As for Aimilia, I loved her in the first two books and heart went out for her in the first two books. I admire how she continue to support Gavril and be his friend even after he broke her heart. The Prince’s vow broke me a little. It was compelling and heartbreaking. So many twists and turns! Many nights I stayed up late reading because I need to see how Nikias and Aimilia’s story unfolded. The slow burn romance was well done! So much yearning and swoony moments. I need the next book after the ending!

[Chantel · Rating 5 out of 5]

This book absolutely riveted and destroyed me beyond my expectations.

I wasn’t a fan of Nikias at first, but after this book, I’m completely invested. Where Gavril and Marcella’s story made my heart ache and warm all at once, Nikias and Aimilia’s seems intent on breaking it. There’s something in their longing, in the quiet desperation of wanting to be chosen for more than what you can give, or seen for something other than what people assume, that hits far too close to home.

Now I’m on the edge of my seat, waiting to see how this love story that feels destined to fail will actually end.

[Hannah Jacobs · Rating 5 out of 5]

What. Did. I. Just. Read? Speechless, angry, devastated, and kicking my feet!!!!

[Liz Hedges · Rating 5 out of 5]

Ahhh! This book had me so wound up I had to drug myself so I could sleep after finishing it at midnight-ish. There’s so much tension. These characters want to make you hug them and slap them simultaneously.

[Amena · Rating 5 out of 5]

Going into this book, I wanted Nikias to both win and lose — and the author did NOT disappoint with any of the drama. (My heart goes out to Aimillia.) Seriously hoping the next book comes soon!

[Leigh W · Rating 5 out of 5]

Aimilia's life has definitely gone in a different direction than she thought. She is mostly over the fact she didn't end up with Gavril, that they weren’t the match she thought they were. But in helping him save Marcella and bring peace she damned herself in the process. The guilt is eating at her daily. While she waits to be free of the palace and finally be given a chance to prove herself as a Commander she finds herself without orders and running into Prince Nikias constantly. Something she truly wishes wouldn't happen since she obviously hates him. When she finds out her grandfather is sick, she demands to be given the chance to see him one last time. Nikias has is own guilt and demons he is trying to hide from. To prove aren't true. And a promise he is determined to keep despite what his scheming mother tries. He knows Aimilia is hiding something, he knows her too well to see through her lies. When presented with the clues he comes to the conclusion she must have feelings for him but is too embarrassed to embrace them after what happened with Gavril. But he is a patient man and wants to show her he can be what she needs just as much as he needs her. When Aimilia requests to go home he finds this to be a perfect way to escape his own guilt that grows within the palace and spend time with his amata. These two start a dance around each other that is cloaked in deception. Will love be found at the end or will it only lead to heartache.

Celeste has a way of making morally gray antagonists in previous books sympathetic protagonists in others. Aimilia was originally Marcella's rival and someone who we didn't immediately like. But this story shows us her flaws, her hero complex, and what lengths she is willing to take for those she calls friends. Nikias was such a great character to hate, especially when he triggered so many of the events in the previous two books. This story lets us see the illusions he hid behind himself and I felt genuinely sorry for the childhood he had. That he had to hide so much of himself and become the focus at times to spare the brother he genuinely loves. And we start to truly see the cracks between him and Faustina that were given to us before in a new light. By the end of the book, I am hoping that the conclusion of this series gives him some semblance of peace he needs. The small bits we get with Gavril and Marcella are bittersweet. This isn't their story now but they aren't quite done telling their tale either. Oh, and that mother. May she get hers.

[Felicitas · Rating 4 out of 5]

More like 3.7 Stars, to be honest. The book was a little too long, and the angst a little too drawn out. (Although well-written and mostly believable. More about that later) Also, when the angst increased, the banter/little barbs between Nikias and Aimilia became less, and I missed them.

But: The book did a great job in explaining why Nikias is the way he is. And how he really is. As well as in explaining the past dynamic between Nikias and Aimilia, and in showing how their relationship gradually changes.

Aimilia is easy to like and easy to root for. She is a great character. She is self-confident and competent, caring and emphatic, but also quite fiery-tempered and does not shy away from confrontations. As a commander, she is used to think things through rationally and look at them from different angles. But she is also emotionally scarred from her relationship with Gavril. Which, of course, affects her relationship to Nikias.

If the book had been shorter, their self-doubts and insecurities would have been more believable. Both are simply too intelligent to NOT realize what the other is feeling and to NOT communicate what they themselve are feeling. Not for 600 pages plus X - because the book does NOT resolve their storyline. At all. It ends on an all-angst high. Urgh. I hate that. Especially if I have to (probably) wait 6 to 12 months for the final volume.
Right now I am emotionally self-medicating by thoroughly hating on the Queen, dear Uncle Cyprian and Faustina. Especially Faustina. There are some very clear hints that the woman has a lot to answer for, Nikias-wise.

[Isabelle · Rating 4 out of 5]

It might be impossible to accurately describe this book, but I’m going to give it a shot. This book felt similar to the previous ones, but at the same time completely different (in a good way). I was quite wary heading into it because I wasn’t a fan of Nikia’s in the first two books, but his character arc pleasantly surprised me. I can be a sucker for a well done redemption arc. I also really enjoyed the progression of Nikia’s and Aimelia’s relationship. One of my biggest pet peeves is insta-love and I can safely say that this book definitely clears that criteria! And can I just say that Celeste Baxendell always does an amazing job with making her characters realistic, almost too realistic at times! I wanted to knock some sense into their heads for how stubborn they both were on certain occasions. Also, that was an evil cliffhanger. I was holding out hope that their story would finish in one book. Now, I have to wait to read the rest of their story! ;) I recommend this to anyone who enjoys character driven romantasy with a splash of angst.

I received an ARC, but was not obligated to review and all opinions are my own.

[Leah · Rating 5 out of 5]

The moment I found out that Nikias and Aimilia would have their own story, I screamed in excitement. Maybe not out loud, but definitely in my head. I loved these characters in the first two books and again in Amata. Nikias has changed a lot since we first met him. I'm with Aimilia on this one, my respect for him has only grown over the course of the series. Also, while I'm talking about characters, his parents are terrible! Even more than what I thought in the past two books. How in the world has Areator continued to have such awful kings and queens between those two and King Sulien's parents? Nonetheless, I'm intrigued.

This book was more perfect than I even imagined. It answered many questions and raised so many more. The ending shocked me, and let me just say how glad I am that it's not the last we'll see of Nikias or Aimilia! I cannot recommend this book enough.

*I beta read this book and then got an early copy from the author's kickstarter campaign. All my opinions are my own.

[Kate · Rating 4 out of 5]

Love, Lies, Politics, and Abuse of Power—4 stars.
Prince Nikias is in love with Commander Aimilia, but is afraid to tell her because he’s afraid she hates him too much to believe him, and he doesn’t want her to use that knowledge against him or pity him. I didn’t like the violence, parental abuse, or abuse of power, but I did like a repentant Nikias trying his best to woo Aimilia and Aimilia’s initial softening towards Nikias. I was disappointed in the ending of the book, and that I have to wait for the next book to come out for certain problems to be resolved. I didn’t like Nikias’s cruel parents, they are pure evil, and wonder why they had such a hold on him that he felt he couldn’t stand up for himself or defend himself when he got older. I also didn’t like the portrayal of physical abuse to women. There are a few people I would like to shake because of their mistreatment of others. There is a fair amount of action, drama, and political problems. I received an ARC copy from the author.

[Michaela | Reading in the Heartland · Rating 5 out of 5]

4.5 stars

This romantic fantasy is both the beginning of a duology and the continuation of a past duology (make sure you read both of those books and the novella Amata first). It was enticing And action, packed and romantic. An enemies to sweethearts extreme slow burn with a reverse brother‘s best friend. With all of the heinous acts he has committed can Prince Nikias ever find redemption? With the weight of blood on her hands, can Aimilia ever find peace or will she be fearful forever? This was a thrilling read that kept me engaged from beginning to end. It is very lengthy and there are many ups and downs and twists and turns that give you whiplash and leave you exhausted and needing the next book in the series. Wonderfully crafted. The romance is just kisses, intimacy level 2. 4.5 stars rounded up to five.

I received an eARC of this book from the author and am voluntarily leaving an honest review.

Content warnings: fighting, wounds, blood

[Mary Elizabeth · Rating 5 out of 5]

This is my favorite series of Celeste's and this book is my favorite of the series! Once we get through some beginning background and interactions with a few characters, the plot shifts clearly to the relationship of Commander Aimilia and Prince Nikias, and the plot is linear reflecting real time. They are so similar in early backgrounds and don't recognize it. Aimilia is focused on perfection and achievement, having definite misperceptions of Nikias, and Nikias has been hiding all the pain he has been through at the hands of his parents. Leave it to Hypatia to sow deliberately distrust, fear, and self-doubt in both of them. Of the two, Aimilia is the one you want to shake and say "wake up!". She is most influenced by Hypatia's predictions which you know were said to Aimilia out of spite to cause problems. The conclusion firmly places you in Nikias' camp, and I can't wait to see where the next book takes us!

[Laura Fincher · Rating 5 out of 5]

"He often wondered how he had ended up here. Painfully, silently, in love with her, even when she was making it very hard to be. Even when he wanted not to be."

I always expect angst in Celeste's books. I mean, the first two books in this series were an absolute rollercoaster of emotion. Nikias and Amalia's story has taken things to a completely different level! I was reading furiously fast, willing and wanting them to finally admit their love for one another. Alas, there is a sequel to their story, so I'm going to need to wait a little longer!

Nikias is a man DOWN BAD. I mean, gosh, his love for Amalia is so tragically beautiful. I love a good redemption arc, and his has been perfection! I feel for Amalia, and the tug-of-war happening between her head and heart. If you're a fan of yearning and star-crossed love, you definitely need to read this book (and all the others before it).

5/5 Stars

Read if you enjoy:
Enemies to Lovers
He Falls First
Redemption Arcs
Touch Her & D!e

*Thank you so much to Celeste for my complimentary copy! All opinions expressed are my own.

[Aunt LoLo · Rating 4 out of 5]

I….man. How do I start this?! This is the third book in the Runes of Pain and Peace series, which is actually a pair of duologies. This duo will see Prince Nikias married to his love Aimailia….or no one. This book had a LOT of drama. I had trouble with the main female character- she was so on again, off again, I kind of wanted to put her in time out. (I have a really low tolerance for drama. That I devoured this book should tell you something!) That said, she is STRONG. So strong. The prince is trying to make up for many many bad choices…and is doing his best. I feel like he's still holding something back. He needs to work through some things to really complete his arc. If you love the knot of the unknown, compounded by many layers of miscommunication, trauma, and drama, HAVE I GOT A BOOK FOR YOU. I received an early copy of this book from the author. All opinions are my own.

[Rachel Wehr · Rating 5 out of 5]

Tormenting.
That's how I feel about this book. 😭🤣
It was a long wait to find out what happens to Nikias and Aimilia, and while not resolved, the wait was worth it. No one weaves a heartbreaking, swoony, action packed story quite like Celeste. From the moment this book opened, it was non-stop action! This did end on a cliff hanger, but I'm not mad about it. (Well, maybe a little mad. 🤣)
All in all, an amazing book, and can't wait to see how this story ends!

What to expect:
👩‍❤️‍💋‍👨 Swoony kisses only
🤬no language-some in world cursing only
🪄Fantasy magic abounds; mages use runes to cast magical spells, and there is a Seer who uses her powers to tell the future
⚔️ there is magical fighting and physical fighting. Wounds are described, but nothing too graphic

[Olivia Grace · Rating 4 out of 5]

I can't wait for the next book! 😭😭
Poor Aimilia! I still don't like Nikias very much but he has slowly been earning back trust. At least with me. He has a long way to go with Aimilia.

This book definitely felt like it developed more of the world and I enjoyed it. The story did seem to go in circles a few times which did make it drag a tiny bit bit not a big issue.

Celeste does an amazing job at writing infuriating parents! 😤😤Or just bad relatives for that matter. 😤Why are they all so dang awful?
Aimilia just needs a break! She hasn't had a proper break since the first book. 😭😭She needs her happy ending!
Thank you to Celeste for the ARC!

[Michelle Pomeroy · Rating 4 out of 5]

So, I've been waiting for this book since The Prince's Mage released. So, for a while now... And it did not disappoint. Except, now I have to wait for the next book!
This is a long read, but Nikias and Aimilia will keep you turning the pages.
The end isn't exactly a cliff-hanger, but it's very clear that this is only the first half of the story and there are a lot of threads to be tied up in the next book.
It's also worth noting that there is abuse in this book (not by the main characters).
This is a clean read and the editing is decent. I received an ARC from the author. I was not required to write a review but chose to do so and the opinions stated are my own.

[Shawna Wood · Rating 4 out of 5]

This was a chunky book to start the year off reading, but it was worth it. Celeste is one of my favorite authors, and she always causes emotional damage in her books, and this is no different.

Celeste is the master of writing angsty, frustrating, slow-burning, and emotional love stories, and Nikias and Aimilia are not different. I loved these characters in the previous book and knew they would make a great couple if they could get out of their own way.

There is a lot of negative history between these two, so a lot to forgive and overcome, plus they live in an unforgiving, brutal world that makes life easy for no one. Nikias and Aimilia will frustrate you, make you scream, yell, and cry in all the best ways possible. A book is not worth reading if it doesn't make you feel, and this will have you feeling all sorts of ways.

I will add that to best enjoy this story and these characters, you will need to read the first two books, but you get away without as the author does a good job of rehashing their backstory.

[Adena Lee · Rating 5 out of 5]

I did not think that the author could make Niklas' story as compelling and as romantic as Gavril's - I was wrong. Niklas' stoic imitation of statuary masks a complex web of pain, self-doubt and longing which rivals any Beast retelling I have read to date. And Amilia as Beauty? Such a feisty, snarky, stabby Beauty she is. I have to see what happens in the next book, because I need to see if the author will write something as heart-wringing as this.

I received an ARC from the author and I am voluntarily leaving a review.

[Shawna Z · Rating 4 out of 5]

What a return back to the world of Imperia and to the chaos that is the Royalty. Both Princes Nikias and Gavril are wreaking havoc simply by being in love with Aimilia and Marcella.

Nikias has been in love with Aimilia for years, even if she once only had eyes for his younger brother, and Gavril’s rushed marriage while bringing his captive bride back to the capital city of Areator a year ago still has him out of favor with his parents.

In fact, if Gavril’s choice of unorthodox bride hadn’t helped to bring a reluctant peace between two hostile factions, there is no way his parents would have even allowed him to step foot back into the city.

Not that Nikias is doing any better, having publicly asked for Aimilia’s hand in marriage and her turning him down. But why let a little thing like public humiliation stop you from trying to win the girl you love.

So when the possibility of another faction threatens that fragile alliance, the brothers and their girls once again ride north in the hopes of finding more information… but it’s not just the possibility of war that threatens the kingdom, but fractures from within as the younger generation must face taking over the very kingdom their elders have been grinding to dust beneath their feet.

Is there really such a thing as following your heart in the midst of chaos, confusion, manipulation and strife? How about when the threat of treason keeps you trapped?

It’s all a mess and that wait until the next book finally resolves all of this is going to be hard, but I have faith it will be worth it in the end.

Completely clean, slow burn, enemies-to-lovers in an already established world setting that is quite unique in that this world is a nod to the Roman empire but with the inclusion of rune magic.

I received an ARC digital copy to help proofread in exchange for an honest review, but, as with all other titles I’ve done for this independent author, I’ve had my own copy on preorder since it went online. I’m happy to be adding this and the upcoming finale to my library collection!

[Rachel Bradley · Rating 5 out of 5]

ARC Review:
Absolutely marvelous!! I loved Marcella and Gavril’s story and didn’t think another could compete with them, however, I am pleasantly surprised and thrilled to be completely wrong about that! My heart is breaking and healing all at once because I did not want to like Nikias’s character from what all transpired in the first set of books just to be honest. I loved this book and can’t wait for the next one to come and finish Aimilia and Nikias’s story! Excellent story with no spice and no cursing!!

[Kate Bullock · Rating 4 out of 5]

I think this could've been marketed as a story from the world of Runes of Pain and Peace. I felt it was a surprise the change of POV. However, if you go into it knowing that, then it keeps you intrigued! I am very interested in how she will wrap it all up, I look forward to knowing the release date of the next book. It felt faster paced than the other two, which I enjoyed. Enemies to lovers trope, clean romance, and political sabotage all in one!

[Debbie Eyre · Rating 5 out of 5]

I loved the first two books and couldn’t wait to dive back into this incredible world and this time it’s Nikias and Aimilia that we follow. We view prince Nikias as the villain but in this his actions change as he tries to show Aimilia a different side. Twists and turns keep us hooked and engaged in this enthralling tale as we see these two incredible, complex characters face their secrets and their own demons, betrayals and heartbreak. It’s so, so good and I cannot wait for the next book!

[Tammy Villiers · Rating 4 out of 5]

Um…okay. Wow!! Celeste is the type of author who never feels afraid to dive into the very depths of her characters—showcasing humanity in such a complex way that many often miss. It’s not always going to be relatable or funny or interesting or even good, but always real!! Can’t wait for more!!


I received an ARC and this is my own review!

[Aliesha · Rating 4 out of 5]

This book picks up the POV of Nikias and Aimilia’s story from the where the first two books in this series left off. There are so many twists and turns to their relationship as well as a very long list of grievances that lie between them. It is full of emotions and forgiveness as well as betrayal and longing. It is a beautiful story and I can’t wait for the continuation in the next book.