Cruel Vow: An Enemies-to-Lovers Dark MM Romance

by Vesper Vane

The protocol was Secure the target. Extract the asset. Do not engage.
He broke all three.

Kieran Blackwell is a ghost. A cleaner for the Thorns Society. A man whose entire existence is defined by "The Partition"—the mental wall that separates the man from the monster. He doesn't ask questions. He doesn't make mistakes. Until he is sent to retrieve Julien Marchetti.

Julien Marchetti is a thief. The disowned son of a dead Architect, he stole the Society’s most dangerous secrets and ran. He expected to be killed. He didn't expect to be caught by a man who looks at him like a tactical problem and touches him like a ruin.

Captured and zip-tied in the back of a grey Fiat, Julien should be terrified. Instead, he’s watching Kieran’s absolute control fracture.

When a kill order is issued for Julien, Kieran faces a choice that isn't in his follow orders and watch Julien die, or break the only vow he’s ever made.

Now, they are running. From Milan to the Alps, from safehouses to the English coast, the hunter has become the shield. But the Society is watching, and the only way out is to go back to exactly where it started.

Half a continent of running. A shattered partition. One cruel vow.
"I didn't save your life to let you go."

CRUEL VOW is Book 2 in the Thorns Society series. It features a high-angst, intense MM romance between a repressed assassin and a defiant thief. Expect extreme forced proximity, hurt/comfort, and a dangerously possessive protector who will burn the world down to keep his target safe.

--- AUTHOR'S CONTENT NOTE ---
This is a Dark Corporate Thriller Romance intended for mature audiences. It contains strong language, graphic violence, high-stakes psychological tension, and intense intimate scenes (including dynamic power exchange). For a detailed list of specific content warnings, please check the "Look Inside" feature or the author's note at the beginning of the book. Read responsibly.

307 pages, Kindle Edition

Published March 27, 2026

Reviews

[Nicole · Rating 4 out of 5]

Review for (Thorns Society-2) Cruel Vow by Vesper Vane

This is the second book in the Thorns Society series by Vesper Vane. I have to say, this being a newer author for me, I couldn't believe how much this story drew me in. The way Vesper Vane weaved this story just made me addicted to seeing what would happen next. This story does have some trigger warnings you need to check out if you have triggers. They are as follows:

Hurt/Comfort
assassins that are repressed
Thief that is very defiant (great mixture)
A protector who is willing to burn the world down to keep the other safe
strong language
psychological tension
graphic violence
power exchange
intense sexy times

There are more, so if you want the more in-depth list, go to the author's page to see them.
This story is about the ghost Kieran. He is the cleaner for the Thorns Society. He does what he is told, period. But that all changes when he is sent to get Julien Marchetti, who is a thief. He is also the disowned son of a deceased architect. Julien steals the Society's most secret files and just takes off. After stealing the files, Julien waits in fear of someone coming for him. He doesn't expect to survive this choice he made. The shock he feels when he meets Kieran, the man who is sent to be taken and not killed by a man who doesn't seem to have any life in his eyes. He is a robot with dead eyes. Julien finds himself tied up in the back of this man's car. But as he watches this man, he sees his dark emotionlessness begin to change. When Kieran is given a kill order, all he wants to do is not kill this man but protect him instead of killing him. Can he go against the Society that he has never questioned before? Will they survive his choices if he protects, not kills, this man who has thawed his emotions and makes him start to feel again? I couldn't put this book down from the first page. As I finished this book, I was thinking, "I need more." Vesper Vane is an author to look out for; they can write a fantastic story that pulls you in.

Nicole Harvey 

[Carla · Rating 5 out of 5]

Deliciously dark!!! Sooooo good!!! It’s just so well written! There are no lines being blurred, they’re absolute annihilated! This isn’t an enemies to lovers, it’s a chaser and chased turn into a couple, becoming someone else, becoming someone they don’t want to be, but must. And… it flows beautifully from the prior book without heavily relying on it. It isn’t a a stand alone, because they both have a running story, but the characters are mostly brand new. And it’s so good! I just loved it! Kieran acts like a robot to protect his sanity, his humanity, but Julien breaks it all, and together, they find a harder path, but one they choose, one that will set them free. It isn’t pretty, it isn’t a rainbows and cupcakes ending, it can’t be, but it’s the only ending possible, and it’s beautiful. It’s inevitable, it’s incredibly satisfying. And the depth of the characters, of how they know each other so well, and how they work together and making things work between them. I can’t wait for the next one, because Margaux… hfhjogwefjbwefjejjr, yes, no words are available for that character, she doesn’t deserve the title of person. I love how they all make hard choices, extremely hard, but so worth it! I loved seeing the darkness of the characters, and how they chose a different path, harder, harsher, but something they need to do, and now, there are four amazing people together against a giant. It isn’t right vs. wrong, it’s beyond that, it’s the only option they have, because anything else is worse. Fantastic read. Now, I just need the next one. And hopefully, Margaux will not show up on a possible fourth book.

I received an advance review copy for free, and I am leaving this review voluntarily.

[Johanna · Rating 5 out of 5]

'CRUEL VOW is Book 2 in the Thorns Society series. It features a high-angst, intense MM romance between a repressed assassin and a defiant thief. Expect extreme forced proximity, hurt/comfort, and a dangerously possessive protector who will burn the world down to keep his target safe.'

The characters were very complex and compelling and dark and obsessive and perfectly steamy together. Plot was intriguing and intense and well paced. World building continues to excel and impress. All in all a great addition to the series. Thoroughly enjoyed and highly recommend.

Grab a copy, kick back and enjoy!.

I received a free copy of this book via Booksprout and am voluntarily leaving a review.

[Jine · Rating 5 out of 5]

Oh this is the literal definition of a slowwwwww burn but dare I say it worth it! The relationship between Kieran and Julian the way it developed was so damn satisfying! Slowly but surely the walls started to come down for both of them! Both realizing that they were used by the machine and decide to face it together! I loved the tracking in the beginning but when he finally caught up with Julian the walls slowly came down! The reunion between Calder and Kieran was worth the stress! I can’t wait for book 3 to see the foursome take down those who need it the most!!

[Mariah Fields · Rating 5 out of 5]

I thoroughly enjoyed this book. Even more so than the first one. I feel like the first book really set up the society and this book dug into the characters and how they are changing and how they are going to change their world. One of my favorite things about this book was Kieran’s inability to accept that he was lying to himself. He kept stating that he wouldn’t do whatever it was and in the next scene say he did it. He kept this battle with himself for a while. I also loved the possessiveness in this book and the intensity between the MMCs. I can’t wait to see what’s next for the society.

[Linda · Rating 4 out of 5]

Kieran is Calder's enforcer for the Society. He is contracted to search, find & bring back alive Julian Marchettie. Julian has stolen secrets from the Society's vault & is on the run. Kieran follows him to different countries & catches him. During captivity, they find a different side to each other. They are not just an enforcer & his captive. I received an advance review copy for free, and I am leaving this review voluntarily.

[The Book Ssirren · Rating 4 out of 5]

This was such a good read. I absolutely loved the way Kieran came undone professionally for Julian. An assassin and a thief go on the run. These two were so intense. The twists and turns in this were awesome. I was on the edge of my seat the entire time while reading this.