Moth by Lily Mayne

When I—along with my best friend and his big purple monster boyfriend—come across a fortress-like raider camp while journeying across the monster-infested Wastes, we stop to deliver a message.
Somehow, that simple pit stop turns into a seemingly impossible quest to get this camp’s missing leader out of the prison where he’s being held and forced to fight monsters and other humans. And I know exactly where it is, because I’ve been there.
Problem is, I’m making this journey with the prickliest and most arrogant guy I’ve ever met, who seems to immediately hate me on sight. Oh, and he’s also half monster. So there’s that. And he’s in love with a raider who definitely does not love him back, and he seems determined to take it out on me. So there’s also that.
But I’m not going to rise to his childish insults and barbed words. I’m not.
I’m also going to try very hard to ignore how mindnumbingly beautiful he is, even when he’s scowling at me.
But the longer we’re out here together, the more I learn about my prickly half monster companion Moth. I realise there’s a reason he’s so closed off and angry. There’s a reason he hates everyone.
There are secrets he’s been keeping, and when I find out what they are, I want to do everything in my power to help him—even though he’s telling me he can’t be helped.