Once Upon a Demon’s Heart

In the past few years I’ve been getting into demon romances. So when I heard about Once Upon a Demon’s Heart by K.M. Moronova, the first in her Cruel Fates duology, I was intrigued. It was originally published last year and is now being republished by Bloom Books.

Alira is a demigod knight stuck in a time loop where she dies at the hand of the demon Blood Knight again and again. This time will be different: To end the war between demigods and demons, she’ll marry him instead. Alira and Kalel must learn to overcome their mutual mistrust and hatred of each other, but there’s a lot of history to get past first. What will a marriage between these enemies look like?

What I Liked:

• Interesting concept. The synopsis captured my interest and seemed different from most of the romantasy books I’ve read so far. (Not the marrying-your-enemy part so much as the time loop that precedes the marriage.) Demigods and demons fighting each other? Fascinating! Enemies becoming reluctant allies? Love to see it!

What Didn’t Work for Me:

• Abusive. Let’s start with the “romance” in this book. I cannot, under any circumstances, get behind any sort of love story between Alira and Kalel. He is completely abusive to her for basically the entire novel. His hatred for her, his constant threats of torture and death, and his unrestrained anger are off-putting, to say the least. And then the sex scenes are really just sexual assault or worse. Kalel took the “enemies” in “enemies to lovers” a little bit too seriously.
• Alira is a passive sad girl. She’s supposedly a demigod and a formidable knight… but we never see that side of her. She’s mostly just mopey, a glutton for punishment, and unwilling to defend herself against Kalel. Her characterization didn’t match up and wasn’t believable.
• Almost no character development. This isn’t a long book, and much of it is taken up by random attacks and anger-fueled sex scenes. It leaves very little room for either Alira or Kalel to grow as characters, and indeed, they don’t. There’s also not much space for their understanding of each other or relationship to develop. Beyond their (rather convenient) heat cycles and frequent “rutting” (their words, not mine!), I don’t see the characters or the plots progressing in a meaningful way. I know there’s a second book, which will presumably show more growth, but it seems too little, too late.
• Not much world-building. I had a hard time envisioning the world they live in, beyond the fact that there are demigods and demons at war with each other, kings on each side, and mortals somewhere living their lives. I originally assumed it was some kind of ancient time setting, but some mentions later in the book had me second-guessing myself. And then there’s the strange time loop that Alira was in, but not enough explanation for that, either. This novel seems to be going on vibes more than anything.

Final Thoughts

Ultimately, Once Upon a Demon’s Heart was rather disappointing. I got through the whole book and was engaged in the story until the end, but many aspects of the book were just not something I could genuinely enjoy. This definitely qualifies as dark romance (or dark romantasy, to be more accurate), and as I general rule, I don’t enjoy those kinds of stories. Leave legitimate toxicity out of my love stories, please and thank you. I don’t plan to continue the Cruel Fates series; the second book, Once Written in Gilded Blood, comes out in August. This book surely has its audience, but it wasn’t the right fit for me.

Special thanks to SOURCEBOOKS Bloom Books and NetGalley for providing me with an ARC of this book!

Get the Book

You can buy Once Upon a Demon’s Heart here – it’s available as a hardcover, paperback, ebook, and audiobook.

Once Upon a Demon’s Heart by K.M. Moronova
Series	Cruel Fates (#1)
Audience	Adult
Genre	Romantasy
Number of Pages	400
Format I Read	Ebook (NetGalley ARC)
Original Publication Date	June 23, 2026 (rerelease)
Publisher	Bloom Books

Official Summary

This is no fairytale—It’s yearning and guilt of two burdened hearts that will leave readers breathless.

Alira, a devoted demigod knight, has found herself trapped in the throes of a brutal curse. A time loop in which the demon kingdom’s Blood Knight kills her every time. She is haunted by the attack she led on the innocent village of Thornhall, and her guilt consumes her from the inside out. After the twentieth time loop, she has finally had enough. Something has to change, lest she die at the Blood Knight’s hand for the rest of time. A choice she hopes she won’t regret—one to end the war between demigods and demons. Alira is shocked when she realizes that she’s marrying the very knight who has slain her so many times.

A daughter of Venus and a duke of demons. Their love is both cursed and destined—a marriage to save the fragility of their kingdoms.

Kalel is as cruel as they come. A devourer who survives on the gilded blood of demigods. He wants to hate her as much as he did when Thornhall fell, but he finds himself warring with his heart over his emotions for her. Together, they unravel the truths of Faultore, that perhaps not everything is as it seems. The gods may be pulling more strings than they should.

It’s not a question of what love can conquer; it is a matter of what they are prepared to demolish in the path of it.