Right... so this is like the first MM story in the Demonica world. 
 Raze is a Seminus demon, i.e. he needs sex constantly to survive and in particular sex with females (humans or demons it does not matter). The key word here is "females", because Raze is a strange unique Seminus demon and for some strange reason he prefers males. 
 The problem is that he cannot survive if there is not a female in the equation. 
 Fayle is his best friend and a succubus demon. She is the one that helps him out every time he is on the verge of dying. But Raze does not really know what exactly Fayle is and how much he depends on her. 
 Slake is a cold-blooded killer (of unknown species) that he was hired to find Fayle and bring her back to her family. He also needs his soul back because he stupidly has given it away a long time ago. When he finds Fayle, he realizes that he is attracted to her best friend i.e. Raze. 
 By the end of the book: 
 *	Fayle will prove to be a bitch 
 *	Slake and Raze will be in love 
 *	Slake will reveal what kind of demon he is and what this means 
 *	A vampire ex lover will appear 
 *	Eidolon will be ecstatic with the very first gay Seminus demon 
 *	Revenant will save the day 
 Overall it is an excellent book, but I really cannot put it in the MM category. (view spoiler)[Slake is not exactly male. (hide spoiler)] 
 Anyway, it is nice revisiting the Underworld General Clinic, meeting old friends such as Eidolon and Revenant and reading another one-of-a-kind love-story with demons.