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Mutable

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To avenge his brother's murder, Cas takes on his shape. He’s afraid of losing his chance at revenge…and terrified of losing his heart to his brother’s lover.

Cas Farling is three things: a refugee in a war that's nearly destroyed his people; an assassin desperate for revenge against the person his sold him out; and a phage carrier—his body shared with an organism that lets him change his appearance at will. He's also marked for death by the local planetary government, and if he can't convince the peace-keeping Imperians that he's actually his deceased brother Beren—young, innocent, and deserving a second chance at life—he'll be murdered as soon as he leaves their encampment.

If Cas dies, he won’t be able to avenge his brother. Lucky for Cas, the Imperians' commander, Rone Basinti, believes he is who he says he is, and is willing to do more than Cas ever dreamed possible to save him—even if it means marrying him.

Too bad he doesn’t know who he’s really marrying…or how far Cas is willing to go to hunt down his prey.

317 pages, Kindle Edition

First published June 11, 2019

12 people are currently reading
73 people want to read

About the author

Cari Z.

133 books537 followers
Cari Z. is a Colorado girl who loves snow and sunshine. She has a wonderful relationship with her husband, a complex relationship with the characters in her head and a sadomasochistic relationship with her exercise routine. She feels like Halloween should happen every month, which is why you get this picture of her, and hopes that you enjoy reading what she's put out there as much as she enjoyed writing it in the first place.

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5 stars
36 (48%)
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27 (36%)
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Displaying 1 - 15 of 15 reviews
Profile Image for QuietlyKat.
672 reviews13 followers
December 10, 2022
Loved it. Loved it, loved it, loved it! Was it perfect? Probably not. Do I care? Absolutely not. I was captivated and highly entertained from start to finish. I had such a hard time putting this one down and when it was in my hands, I was thoroughly engaged. So engaged that I really didn’t want it to end. The ending was satisfying but I would love a sequel, I just want MORE of this world, this couple and their family. I’m greedy that way.

Love and hugs y’all! Happy reading 😘💛
Profile Image for UltraMeital.
1,283 reviews49 followers
April 19, 2022
WHY and HOW did I wait this long to read this wonderful story? It's the usual, I'm not a fan of Sci-Fi and yet AGAIN I find myself immersed in Cari's characters and story, unable to put the book aside. So there are "aliens" and "mutants" and different galaxies in the unknown future, so what? Everything else about the story of Rone and Cas was simply AMAZING. Well, not to them, most of the time or at least not till the very end. I'm not sure what I think of the ending. It WAS good and yet I'll admit I was surprised, wondering how things will work out. Hoping Cari re-visits these two that's for sure. And as usual not understanding why this is a free read on Cari's blog when she DEFINITELY should be paid for her wonderful work.

Cas Farling has grown up in the planet of Leelinge, but his nation - the Delacoeur - have been fugitives in this planet ever since they arrived from their own uninhabitable planet. Hiding in caves they assimilated as best as they could, some of them, the strongest ones, being able to accept into their body a sort of bacteria they call "Phage" enhancing their physical abilities (and making them excellent trained assassins). Yet his kind was betrayed - by someone of their own and now there are so few of them left.. and only one other who like him contains a Phage inside him - Christala. Cas deduced she must be the one to play a huge part of the betrayal who cost him his little brother Beren as well.

Now is his time to escape this hated planet as well as hunt Christala and the others when a ship from the planet Imperia is there to take with them anyone willing (who isn't infected by said bacteria..). Unable to mask his Phase when his blood is drawn he finds himself in the worst situation possible. The people from Leelinge KNOW he at the base and so if he won't be leaving with the Imperia ship, they'll expect him to leave and once he does they'll be waiting for him and though he masked his appearance to the one of his younger brother Beren, he won't fool THEM and anyway they won't care, they'll kill him for just being a Delacoeur.

Trying to make SOMEONE at the base help him, re-take the blood test or ANYTHING really he finds an unexpected ally in Captain Rone Basinti. He doesn't know his good fortune and the power this man has, he just knows the tenderness and care in his eyes might be his only hope and though he isn't thrilled about lying and cheating the only person who is willing to help him he does that with a heavy heart. He will avenge his people, he will avenge Beren.

Rone's proposition for Cas, or as he introduces himself as - Beren - is an ACTUAL proportions of marriage. That's the only idea Rone has to shield him and actually it's not a bad idea as he is in need of a "nanny" for his two adopted kids (also not Imperia natives) and since that's one of the qualifications Beren offers (after all, what kind of education do you expect from someone who grew up in caves in constant fear of death). Cas is more than puzzled by the trust of the Imperians but it plays into his favor so why fight it? A marriage it is.

Rone is honorable, sincere and fair. Everything Cas doesn't believe he is owed especially with his ulterior motives but spending time with Rone makes him question his actions, not wanting to hurt the guy and even learning to care for him even if Rone only sees someone he really isn't - the brother he should have been able to save and wasn't able to. Rone does everything to make Cas comfortable, on the ship, in his own home and even in the palace. What he's doing in the palace? Rone is a lot more than just Captain, he is the illegitimate son of the previous king - the brother of the current kind. This makes Cas life on the one hand easier yet in so many different ways A LOT more complicated.

I can say more but I rather not. There is so much going on in this book. A bit of everything really, though the romance is VERY slow going considering both don't truly trust one another (as would be expected..). Besides two chapters we only get Cas's POV so it's hard knowing what Rone understands or sees in his husband's behavior as he has his own secrets..

This was SUCH an engaging read. The chapters were rather short as this story was published in half chapters in Cari's blog (now finally available to purchase as a full length novel). I think I would have DIED if I had to wait a week for each chapter so though I'm mad at myself for waiting this long to read it, I wouldn't have done it before this one was totally finished. This is actually my final read of Cari's published work, only thing is the current story "The Tank" she is publishing the same way - a chapter each week. It's going to be over soon so I'll delve into it once it's finally done as well.

HIGHLY RECOMMENDED!!!!

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Profile Image for Tia.
586 reviews1 follower
July 3, 2023
Definitely some big gaps in the world building and the phage - but still a totally captivating read anyway. I would have liked more from Rone, but Cas was still a ruthless delight.
Profile Image for 空.
799 reviews14 followers
January 5, 2026
It was interesting, but the marriage is really just a plot device. Cari Z focuses much more on the revenge plot, which I totally get. But:

✦ The relationship does fall by the wayside. There’s unfortunately not a lot of pining or even a lot of romantic interaction between Cas/Beren and Rone. It feels like it’s taken for granted that they are in love and that they somehow became loyal to each other for … well, unclear reasons.

✦ The timeline is also not clear. How much more time did Christala have that she could infiltrate the palace and even place the King’s cousin under thrall? Months? If she did you’d think she’d have been able to cover her tracks more carefully instead of Cas/Beren being able to pin down her ~*secret identity*~ after reviewing (however carefully) a bunch of profiles. (Granted she was apparently also dumb enough to use the identity of a dead Delacoeurian...)

✦ The phage also isn’t clear. Doesn’t it propagate? Can’t it make more of itself? What, is there a fixed amount? Also why does this phage give humans visions of grandeur? My understanding is that Christala gave into the phage’s visions, and she imagined herself as becoming Queen —



— but if she’s stretched so thin then how was she able to change shapes?? And if the phage doesn’t propagate how can she keep enthralling people? She can enthrall ten people at the same time, but the implication seems to be that she can drip and drab if it’s not ten in one go. But then the phage should be able to regenerate, right? But then why did like the entire phage jump to Rone? I DON’T GET IT. But then why should I ask for reasoning from a virus?? BUT THEN THE PHAGE DID “ASK” TO GO BACK TO CAS THOUGH. AGHH.

✦ There’s a lot of tough topics here but Z chooses to just go with the simplest route, which again, I understand. But if that’s the case, girl, don’t bring up what is potentially the genocide of the Delacoeurians and then just handwave it all away with an “at least Cas is alive and happy ;)” ending.

Yeah we need to have drama and character motivation but at the same time that is real heavy just to have a quick marriage of convenience romance novel where the marriage of convenience doesn’t even have delicious pining.
This entire review has been hidden because of spoilers.
Profile Image for Boyslove.
264 reviews24 followers
April 24, 2024
This is the first book I’ve been able to finish in months and I loved it!

There was enough exciting moments, compelling story elements and believable dramatics that I love in books. It was just the perfect amount of suspense, action, angst and heartache while still keeping the romance situation very meaningful.

Something that this author does really well is making you care about the main characters, I really like how she tends to have one of her main characters be more noble and honorable.
Profile Image for Pirefly.
3 reviews4 followers
April 15, 2022
An amazing read loved the characters and was such an awesome and unique idea for a story.

It definitely would have been a re-read for me if the ending hadn't felt a bit rushed.
Profile Image for Amy.
2,065 reviews39 followers
April 17, 2022
I loved this story and the characters. The Phage sort of reminded of Venom in a way, especially toward the end. I really wish the ending was a bit longer.
Profile Image for M.
283 reviews12 followers
May 21, 2022
Starts out great, an interesting sf plot but after a few chapters the plot just seems to get lost, throwing royalty and children (the children plot was really annoying) and more and more unlikely things. Also the relationship itself is almost secondary, both sexual tension and romance.
Profile Image for Dr susan.
3,072 reviews51 followers
April 17, 2023
Wow! Fantastic romantic sci fi adventure

The worldbuilding is great, albeit grim, and the story is a thriller. There is graphic violence and a very sad body count (I'm not getting over one character death any time soon). The epilogue has graphic sex. Cas and Rone are an interesting couple with a lot of unexpected secrets, leading to some intriguing plot twists. Honestly, I was not expecting Mutable to be as good as it is. I read it in KU but plan to buy it to reread.
Profile Image for Mai.
319 reviews5 followers
July 13, 2025
This one is great. The worldbuilding, the relationship between MCs, Cas’ internal struggle, the few glimpses into Beren’s POV and Beren’s backstory… 10/10
Profile Image for Ridley.
96 reviews
October 29, 2021
cover

Humanity set out to the stars hundreds of years ago and colonized the distant Tiresias System on several planets. But since they are still humans, they still struggle with selfishness and xenophobia.

Those who set out for the planet Delacoeur barely made it of planet again, and fled to the next planet Leelinge. They fought a loosing battle against the established population, just to be tolerated to be living in caves nobody dared to enter. But the found something there... something that gave some of them an edge like nothing else.

But when the Delacoeurians are betrayed by one of their own, it all falls apart. Most of them die, Cas is out for revenge to avenge all he had lost. And he is willing to do anything to do it. Lie, cheat and steal or marring a prince to get off planet. A prince who is not at all one in a shining amore, but one with eyes shining purple sometimes.

I'm not sure if I really like blog stories cause they tend to meander about sometimes. But this one was just great. I liked the characters, the world and there was always tension.

If you like fast paced stories where the romance aspect is there but not in the main focus, this one is for you. Read it while its free, cause this gem should be published at some point.

There are a few minor things. I did not get the insta love for the kids. And both of the MC seemed a bit too wholesome for having actively participated in war atrocities. On the other hand they are both pretty bad ass. Maybe getting into all of that might have be the rabbit hole, which might have cost this story it's drive.
Profile Image for Dragonfriend .
112 reviews2 followers
April 19, 2024
3.5 There were a lot of good, creative ideas and the beginning of some good world building, but it didn’t quite go into enough detail. Could've used more background development, I thought. Could've gone a little deeper into the story and background of the plot. I think it would've been better if we'd learned more about the Leelingers instead of just saying that they are evil. I wanted more on the history and conflict between Leelingers and Delacoeurians in general. Also would've liked more about Cas's life before losing Beren, maybe through flashbacks. I was also annoyed that a group called the Imperions, so called for their imperialism and tendency to look down on everyone it seems, ended up winning out in the end, but that's just me. I think that’s mostly what caused me to take off points really, how we touched on the ethical issues surrounding Cas’s position, but then shied away from exploring it. I feel like Cas, being a character that was so centered in the planet's conflict, should have had more passion and depth to his feelings about all of this. Especially since I feel like this story told from the point of view of the Leelingers would’ve been very different. I wanted more exploration of that.
This entire review has been hidden because of spoilers.
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