Check out this review and more at On the Wings of Books 
 Warning: There will be spoilers for the first book in the series, Obsidian. 
 What I Thought... 
 * It's quite possible the romantic tension between Katy and Daemon will kill me. There is so much and I just want to yell at them to get over it already. 
 * Katy is going through lots of weird stuff in Onyx. After Daemon healed her in Obsidian she is having some very uncomfortable after effects. 
 * There is a new student at school, Blake. I was really worried that this was going to turn into a love triangle, but even though it kind of almost was a love triangle, it really wasn't. Every time she was with Blake she was thinking about Daemon. 
 * Daemon does quite a bit of changing in Onyx. He's still a bit of jerk, but since he's decided to stop fighting his attraction to Katy he's being much nicer. He goes through a couple of not so nice phases, but you kind of understand why. 
 * TRUST NO ONE!!!! 
 * Seriously, Armentrout does not allow you to fully trust anyone. Things can change on a dime. 
 * We see a lot more of the other Luxen siblings, Adam, Andrew and Ash. Ash was impossible in Obsidian, but I've come around to her a bit in Onyx. I like that the Luxen themselves are like a family and will protect one another the best they can. 
 * My heart broke a little bit at the end. It's just not fair for authors to do that! (view spoiler)[I was upset enough about Adam, but the whole thing with Will and her mom broke my heart a little more. Her mom doesn't need more suffering. (hide spoiler)] 
 * I still feel that aliens that look like humans is a bit of a cop out, but I suppose that's the only way that you could get this whole human/alien thing to work. I guess the reason why these alien books work so well for me is because I don't really feel like I'm reading about aliens, which is fine with me as I don't really like them. (I also really like that we're just chillin on planet earth). 
 Overall Onyx is a great second book in the series and I can't wait to read the rest!