Dragon Blood Curse

Emperor's Assassin #4

by Kai Butler

The generals that once served Emperor Tallu now pursue us across the continent. We have one chance to save our lives, one hope at a future that we both so desperately want. With new allies and old nemeses, we have to risk our lives to create a world for our love.

Genres: Fantasy, M M Romance, Dragons, Romance, Royalty, LGBT, Queer

379 pages, Kindle Edition

Published March 16, 2026

About the author

Kai has been reading and writing romance novels since she was a teenager. She lives in California with her two children and her very supportive husband.

She writes M/M romance with an emphasis on HEAs and all the feels. Her current series are San Amaro Investigations and the Imperial Space Regency Novels. She likes dashing heroes and couples with banter.

Reviews

[Alexia · Rating 4 out of 5]

I debated extensively with myself about what rating to assign to this book, and even now, I remain uncertain. I genuinely enjoy this series and I give high ratings to all its installments, yet there was always something holding it back from becoming a personal favorite. Until this book, I couldn't quite identify what that was.

Now I understand, it's the side characters.

Let's start with the world-building, as the author has crafted an intricate and richly layered universe. The depth and detail are so impressive that it feels as though one could flip open a history book and learn everything about this world. Each installment expands on the lore, revealing the customs, traditions, and histories of numerous nations, illustrating their rises and falls across the ages.

Next, the political intrigue deserves special mention for its masterful execution. The complexity of the schemes, the multiple levels of deception, and shifting alliances create a narrative so sophisticated that it closely mirrors real-life politics. The author’s skill in portraying such layered, realistic political maneuvering is truly commendable, and it consistently keeps me engaged and eager to see how conflicts unfold.

Having discussed what I most adore about this series, I must also confess what frustrates me so profoundly, namely, the side characters. They are overwhelmingly obnoxious and irritating, often stepping on my nerves and provoking tears of frustration. There have been moments when I harbored such strong feelings of disdain that I would have gladly seen them meet a cruel fate, and I wouldn’t have been upset. It’s not that they are bad or good, but their actions drive me to scream at my book in exasperation. These characters are neither stupid nor simple, in fact, they are layered, well-developed, and have backstories that justify their motives. Yet, their complexities only deepen my annoyance and dislike.

Getting that off my chest, I can now turn to my favorites, Airón and Tallu. Despite some moments of annoyance, I truly love them. Airón is a protagonist who may not win everyone’s admiration. His assassination skills are flawed, and he often makes poor decisions. However, his growth over the course of these four books transforms him into a character who commands respect. His evolution, fraught with mistakes and lessons, makes him more relatable.

Tallu is the archetype of the tortured love interest, eager to distance himself from his heinous family and their sins. What sets him apart is the way he is written, which doesn’t evoke overwhelming pity or frustration but instead inspires genuine love. His desire to dismantle the corrupt foundation his family built(regardless of personal cost)paints him as a deeply layered and complex character. He genuinely wishes to see justice served, even if it means destroying himself in the process.

Their relationship, although primarily a subplot within the larger narrative, is profoundly touching whenever depicted. Their mutual love and unwavering commitment to each other are palpable. They care so deeply that they would risk everything, including their own lives, to protect the other. Their tenderness, communication, and the strength they find in each other exemplify what true love should be: not a source of pain but a source of empowerment.

In conclusion, the way this book ended has left me eagerly awaiting the next installment, book five. Despite my hatred for the side characters, Airón and Tallu constantly rescue this series for me, reaffirming my dedication and excitement to see how their stories continue to unfold.

[Sam Reads Books *Just the Highlights* · Rating 4 out of 5]

2026: 4.0

[Jinx · Rating 2 out of 5]

I feel like the author has really lost the plot of this series for the sole purpose of stretching it out. This book dragged so bad. It was page after page of nothingness. There was no forward movement to the story at all. I also felt this disconnect with Airón and Tallu. They spent a lot of chapters apart where Airón would risk his life and wellbeing all in the name of saving Tallu but the sacrifices never seemed to go anywhere. It was just one reckless decision after the other with no successful outcome and that at the end of the day moved the story nowhere. The only thing to come out of this book was a new cast of side characters that don’t feel important to the plot but also feel like a red-herring. Cos why would the author introduce them unless they were expendable or a last minute plot-twist villain? These books have gone from my most anticipated read to not knowing if I’m gong to continue reading this series.

[Mimi]

I think I might be getting tired of this series bc I gobbled up the previous books but am having a hard time with this one.

The plot picks up with immediate action right from where the last book left off and it felt very disconcerting. There was no break to gather my bearings, you’re immediately thrust into all the intrigue. I read the last book only a few months ago, and still felt very lost. I fear that folks who haven’t read the last book immediately before this are going to have a hard time.

It also feels like the romance has taken a complete backseat to the plot. This wouldn’t be as much of a problem if we got other POVs, but bc we only get one MC’s POV, so this epic plot and world building starts feeling very narrow and constricted.

I prefer Hailey Turner’s approach to the Infernal War series than the way this series is evolving. It’s too many books from only one character’s POV for such a epic heavy plot and it’s all feeling very chosen one focused bc of that. Hence why I’m having a really hard time with my rating even tho I really enjoyed the previous books.

[Kristine · Rating 4 out of 5]

4.25 Stars ⭐️

I have really enjoyed this series and have fallen in love with both Prince Airón and Emperor Tallu. In this book, the two of them are dealing with the mutiny from their two Generals and are trying to come up with alternate strategies.

They end up taking a route by water that doesn't exactly turn out the way they had planned. In the meantime, there are discoveries being made about what exactly is going on at some of the other areas - elven areas that are yielding some major surprises.

This book felt a little slower than the previous books, but it still did move the overall storyline forward. Tallu now has his younger brother and Heir with them, along with the former Emperess but he is not completely convinced of her loyalties.

As usual, this book did give us just enough to have some major information uncovered, but unfortunately, it left us with more questions than answers.

It looks like I will again be eagerly awaiting the next installment :)

[Melanie · Rating 5 out of 5]

exciting, entertaining read

Rating: 4.5🌈

Dragon Blood Curse was an exciting, immersive experience all around, as Butler’s penultimate story brings more mythical characters and magical regions into play with this fantasy action adventure.

Prince Airón and King Tallu have multiple schemes at work and not all are going according to their intended intentions. With their enemies bringing larger powers and armies against them, Airón and Tallu race to find a cure for the deadly curse that affects both brothers. And their own council falls into chaos and loyalties are divided as the enemy attacks.

It’s high politics, subterfuge, magical terrorists, and wars between enemies being waged across their borders and territories, and everything and everyone suffering.

Of course, there’s a prophecy or two, sacrifices that figures mightily in the coming novel, angst and some really great layering of information and people (look to the North) that just ups the stakes here.

No spoilers but this just grabs the reader from start to finish. For me, the relationship between Airón and Tallu is the least compelling element here. So many other great aspects of the series and story to focus on.

Great job. And I love the Spider. Awesome.

Cover by Hannah Latham at oexasart Lettering by Laura at Covers by Aura

Emperor's Assassin (5 book series)
Betrothed to the Emperor #1
Emperor's Wrath #2
Shadow Throne King #3
Dragon Blood Curse #4
Crown of Ash #5 - Oct 26,2026

[Rasa || beviltiska_romantike · Rating 5 out of 5]

4.5*
"What I am going to do with you, if you insist on throwing yourself into danger?" Tallu asked.
"Love me half as much as I love you", I said.

[Ailyne · Rating 4 out of 5]

Im really going to need my boys to have a HEA because I AM TIRED!

[maqready · Rating 5 out of 5]

this book is my favorite of the series so far.
the tragedy and ruin brought to Tavornai and its people by the evil genocidal empire hit too close to home, unfortunately, i could barely hold back tears at times. and it's gonna be even worse going further to other conquered lands 💔
and yet i can't wait for the next book.
.
.
.
.
ps. Kennelmaster, pls live, im begging you.

[Florian]

YES!

I'm so invested, I really really hope Kai Butler doesn't stop writing the Emperor's Assassin saga at least for another four books. (Please and thank you.)

I had such a visceral reaction to some parts with the maritime horrors I haven't experienced since The Odyssey. And in a way, it was a modern Odyssey, really. Especially considering Airón's emotional journey: his newfound empathy for the imperials, whose lives he now treasures, the camaraderie with the soldiers and his guilt when they died because of him, his loss and grief and sacrifice...and all that for almost nothing. Absolutely brilliant!

The first books are good too, but I feel like the series gets exponentially better and better with each new turn, while the style stays consistent. It's bloody marvellous! Little things I was hoping would happen, happened, new fascinating things were revealed, this could easily go on for a long time, there's so much potential.

Some side characters honestly deserve their own books.
Sagam, of course. He had always been interesting, and he's just became even more so.
But also Lord Chaliko! One cannot read the annihilation and forced reeducation of elves without finding direct parallels to our real world, and the fact that he attempted to save lives not once, but twice, in absolute defiance of the Emperor's orders! I want to know the man.
Also also Homisu! We barely know this guy, but I love him. His keen expertise, kind heart and that sword strapped to his waist...like, who are you?

Some of my personal highlights:
• "I have to appreciate how you never bring us easy problems, General Saxu." This line was so cliché but so awesome. Very old-school adventure film line, very cool.
•Loved that the soldiers got the real side of Airón in that little night swim. It could potentially lead to great things in the future.
•I was thrilled when Airón's skin and hair changed after forest magic! Tallu's reaction to that was also very satisfactory.
•YES, finally the fire power is awakened!
•Also the fact that it seems Airón will be an omnipotent being very soon, oooh, I hope that's where we're going.
•Tallu braiding Airón's hair! This is not a drill!
• I just love horny Tallu. That's it.

Now some things that made me frown:
• Prince Hallu is less than four years old, even if he's raised as the future emperor, he would not speak like that AND most definitely wouldn't ask THAT. I do suspend my disbelief, believe me, but that's just a no. Maybe a very mature seven-year-old, raised by mind games and court gossip, but not an almost toddler. (Unless there's a magical explanation.)
•Spider said that Airón sacrificed memories and power. What power?
•Why didn't Airón try his healing magic on Tallu before?
•The whole uniting the Empire prophecy always made me ponder why they didn't think of a peaceful solution instead of the conquering all the land method. And now you're telling me that's actually the KEY TO THIS WHOLE THING?! It's a bit anticlimactic. It's not bad, but soooo obvious I don't know how these smart characters didn't think of that sooner. Or maybe I'm missing something.
•Why is General Namati asking to rule Tavornai if he is in love with Spider who obviously wants elven independence in Tavornai, no?
•"Tallu would fashion himself into the bloodthirsty tyrant he had fought against becoming to create peace..." Impactful line. But...I'm sorry? Why is that necessary? Yes, he will wage war against the usurping generals, but why would anyone (except the generals' supporters) in the empire think he is bloodthirsty?
• This did not make me frown, but I dearly wish for a timeline with all the Emperors of House Atobe and their rules in addition to the map. That would be useful.

[Ariana (mostly offline) · Rating 3 out of 5]

3,5 stars

I started this book 3 times, abandoning it twice because there is so much political talk and intrigue in the first 20 to 30%. And virtually no Tallu and Airon.

I persevered the last time and things do get better later on. I’ll not lie, I found the very much action (rather than romance) based plot a bit too much for me. (Tbh, I know this is the author’s style, so I shouldn’t complain.)

However, I always struggle with a huge amount of names and characters. Once I decided not to worry about that and accepted that I didn’t necessarily need to know or remember every single person mentioned and to understand every political decision to get the gist of things, reading felt a bit lighter.

Tallu and Airon are trying to find Spider in this book because they believe that this animalia can help Tallu beat his curse. I enjoyed that treacherous journey and all it entails.
Interesting that Airon seems to accumulate a lot different magic along the way which surely, ultimately, will lead to a point where he needs to use it.
I also liked the whole philosophy surrounding the elder trees which reminded me of the San Amaro series by this author. There’s clearly a very strong message here I wholly approve of.

Tbh, my main problem with this series is that I still can’t fully connect with Airon.
He still irritates me. In things he says or does or thinks (we are in his POV only). There is this certain arrogance, this vibe of ‘know it all’ that makes me want to shake him. But it isn’t that alone, and while I really can’t put my finger on my issue with him exactly, I guess it simply comes down to me not gelling with him. Sigh.

But, I guess I will be back anyway to see where the next book takes Tallu and Airon.

[Dalegendaryreader · Rating 4 out of 5]

“I want you. I want a life with you. That is not possible as long as the Imperium survives.”

The generals that once served Emperor Tallu have the Imperium and declared war. Emperor Tallu and Prince Consort Airón have to find new allies at the same time embark on a secret journey to save their lives.

Started reading this during release day because ya girl couldn't wait but I also saw the next book gonna be published this October so I debated whether to binge-read this or savor. I chose savoring the book.

Ngl, the reason why this was not a 5-star book was because of all the travel. I get it, it's a fantasy book and they have to travel but dang, I don't really like the travel aspect in books. Not the book's fault, but it's me.

“Tallu, I cannot save you if I lose you first.”

I love how much more high stakes we are. Every book and in every journey is one step closer to Emperor Tallu and Prince Consort Airón's end goal. I love it sm! The adventure, the way the politics works, it was amazing on how the author wove together the story. You can see there's a way and that everything is a stepping stone.

“It is better when you are with me.”

The romance sprinkled in here was so endearing. We know what are at stakes and yet we can definitely see how fiercely Tallu and Airón loves one another.

I cannot wait for October please.

[SNik · Rating 5 out of 5]

Fourth in series (Emperor’s Assassin), must be read in order. Fantasy. Established couple. Found family. Single POV.

Immediately following book 3, Airón and Tallu remain intent on tearing apart the empire, however they are racing against time as they are pursued by the traitor generals and trying to find a way to end Tallu’s blood curse.

Since Airón and Tallu are solidly in love and committed to each other in all ways, this story hits harder with Airón’s desperation to save Tallu. The journey across the empire still has them deep in political intrigue and trying to survive as they juggle the outward appearance of trying to save the empire while secretly planning its demise. As the story is told from Airón’s POV, it was fun to read as Airón is super capable and a main character to root for, his love for Tallu drives all his actions, and he is admirable and intelligent as well. I thoroughly enjoyed this entry in the series, the group of supportive characters that are loyal, the commitment Airón and Tallu have to each other, and the overarching hope to bring about a better empire.

[Copper · Rating 4 out of 5]

Catching back up with Airón and Tallu as they continue their secret mission for the good of the empire and their own happiness. More court politics and political manoeuvring going on to keep you interested. But also a lot more history on the land and the people of the extended empire.

Seeing everything from Airón gives him a strong voice and I find his thinking can be hit or miss, giving interesting outcomes for both. This also gives Tallu some mystery over his interworking, although at this stage of the story they are both so manly in love that he's mostly thinking of the empire or Airón. I love how the pair have grown together and deeply love each other now.

Also love the pair of dogs Asahi and Sagam I wish we saw more so excited they are getting their own book soon. I find their love story so sweet but tragic, I really hope they can build some happiness.

Looking forward to the next book, the last few chapters here really had me going. I'm interested in how this next installment will play out after the event in this one.

[Es :D · Rating 5 out of 5]

This book was so good. 5 stars for me. The relationship of Tallu and Airón deepens, and we get to see more of their love for each other.

We also learn more about Sagram, who was a bit more a minor/side character in the first few books. We learn more about his family and origin.

I also love the fact that we get to see more of Airón’s power in this story. He’s really powerful, and we get a contrast later in the story. ( spoilers) About him and Seagram’s sister, Riini. Riini sacrificed almost everything in her life to try and regrow an elder tree. While Airón easily grew many with his memories.

It saddens me that Tallu has to accept his bloodline, and become someone he desperately tried not to become. I guess the title of the fifth and final book, Crown of Ash, suggests what might happen at the end of this series.

“I am going to save you, Tallu.” I gripped his face between my hands. “Do you hear me?”
“You regrew an elder tree for me?” He let my braid slip from his fingers, lifting another.
“I learned forest magic for you,” I said.

[Avid Reader 1 · Rating 4 out of 5]

4 ¼ Stars

Dragon Blood Curse is a great continuation of the Emperor's Assassin series. I strongly recommend rereading previous books in this series before reading this one.
Tallu and Airón continue to support each other and their goals for the empire's future. There is A LOT of political talk in the first half of the book. It lost my focus at times, but I’m not a big political person, so I guess that’s a “me” thing. Many of the characters will receive the side-eye since I have become suspicious of almost everyone on these pages. The depth of the characters and the worldbuilding in general continue to impress me.
Airón and Tallu are wonderful main characters, and I feel closer to them with each successive book. Even with the single POV, I know Tallu just as well as I know Airón.
I am invested in the lives and HEA of these two and in the outcome of their political partnership.
I look forward to more from this author.

[She Who Shall Remain Nameless · Rating 5 out of 5]

Excellent new addition to the series! I highly recommend rereading the previous book in this series before reading the new releases just to reacquaint yourself with the storyline. I purchased this book directly from the author, which I highly recommend as a way to both support your favorite authors and not spend money with Amazon. This book helps further Airon and Tallu’s quest. There was a bit more political intrigue in the first half of the book than I prefer, but the second half had a bit more action to it. Overall, this is an excellent series which I highly recommend. I can’t wait for book 5 to be released.

[Juniper · Rating 5 out of 5]

This is book 4 in the series, and a gentle note to readers that starting at the beginning is a good idea. This book delivers everything that’s made this series so compelling: immersive, layered world building that blends magic, intrigue, wonder, and genuine peril in a way that never loses its sense of stakes, and absolutely no dull moments (plenty happens, and I’ll leave it at that — the plot deserves to be experienced on its own terms). What anchors it all, though, is Tallu and Airon, whose connection is a real source of strength and depth — for each other and for the story.

*I voluntarily reviewed a complimentary copy of this book

[Deanna · Rating 5 out of 5]

This series is so good. Like the others, this book catches you and drags you in from start to end. There's more politics (which Airon might think he's bad at but I think he's catching on) more magic, more blood. More sacrifce. The journey to save Tallu and Hallu continues, and the prophecy which started this whole mess becomes clearer. Kai Butler's writing is so rich - the journey through the empire and Tavournai itself was so brilliantly described it felt like I was there. I worry for Asahi and Sagam, and Iradio. Looking forward to the next book.

[SandyB · Rating 5 out of 5]

What started as a story of court politics and arranged marriage machinations has grown into an epic fantasy with political intrigue, amazing worldbuilding, and high adventure. Picking up right after the last one (read in order!), Airon and Tallu deal with magic gone awry, forces beyond their control (maybe), and traitors big and small. Every character has purpose and is fully developed, every event has ramifications throughout the rest of the book. I savored every bit of it.

[nikkie · Rating 5 out of 5]

pleaseee please read this series!! wow i have been so captivated since the start!!!!! there is never a dull moment, and i am never lost (i am very easily confused, so that means a lot LMAO)
i am sapphic and dont usually read mlm books but i love this series so much, i dont even know how to put it into words. i never want to put the four of these books down, and i have already pre-ordered the fifth! so excited to read more!! i dont want it to ever end!!

[Jewel · Rating 5 out of 5]

I am LOVING this series. Tallu and Airón have been through so much and there is more yet to come. I think I will reread the whole series before book 5 comes out.

This series has so much I love in a fantasy story - magic, intrigue, bratty dragons, even brattier ravens, curses, adventure, quests, loss, and love. *chef's kiss*

[Cath · Rating 3 out of 5]

Pensaba que era el último libro de la saga y me estaba rayando mazo mientras lo leía ajjajaj

No me ha gustado nada cómo estaba escrito, es que es me sacaba mucho de la lectura, no se si solo soy yo o qué cojoneh, pero era muy raro, aun así estaba interesante y solo espero que mis bebés puedan ser felices para siempre.

[read b00ks · Rating 5 out of 5]

This is possibly my favorite fantasy series. I love Tallu and Airon. Yet again they're faced with nearly impossible obstacles and surrounded by people they can't trust. Just when they've got a handle on it, a new issue pops up. I can't wait to see what happens next.

[Noah Shoshan · Rating 4 out of 5]

4.75/5. Listened on audible. HOLY FUCK! Best novel in the series so far. The first part kinda dragged a little but as soon as it picked up in the middle, it was brilliant. I hope in the next novel we will see a bit more of Sagam and Asahi’s relationship. Now I have to wait until the next book

[Dee · Rating 4 out of 5]

This was my least favorite of the series thus far but was still a well written story. I think there was significantly less relationship building and lovin’ on each other between the MCs, so that’s probably where most of my gripes stem from lol

[company_in_misery · Rating 4 out of 5]

Можливо, тому що у мене була перерва між попередніми книгами і цією, але повертатись в цей світ було важче.

Принц-консорт все ще поки "найкращий марті с'ю", якого я зустрічала, але історія, на мою думку, починає трохи себе виснажувати. Прокляття Таллу потроху втрачає страшну невідворотню форму, якою нас спершу лякали і це для мене сильно змінює атмосферу (

Можливо, також мені не дуже подобається до чого у нас підводить сюжет надалі.

[Brittany · Rating 5 out of 5]

Bittersweet

Our sweet Prince cant catch a break. Most of this book stressed me to the max. I was sure he would lose himself because of his love for the emperor.
And that promise from the spider. Didn't sound like an happy ending.

[Jane Pigliacelli · Rating 5 out of 5]

LETS GOOOOO IM SO EXCITED

[Emma · Rating 5 out of 5]

(Proper review to come)
Ugh I love this series so much and I desperately need more