Eidolon is a demon and a doctor and the founder of the only demon hospital. A hospital where all lucky demons can visit, get well, not kill each other and then run free to torture more humans .... or not. 
 And of course in this hospital no humans are allowed, since humans are the worst race that walks on earth (according to the Demon Bible of course). 
 And then Eidolon's future lady, Tayla Mancuso, appears who is human, wounded and about to die and Eidolon decides to make her feel better in every possible way (deep sigh...). 
 Tayla basically has three secrets: 
 1 she likes killing demons because demons are bad (ha ha) 
 2 she cannot orgasm (poor Eidolon!) 
 3 the last secret will be revealed while you read the book and will be a surprise for her as well 
 I absolutely adore Eidolon. He is on my top ten list of desirable paranormal guys that although I have a crush on them, I do not want particularly to meet in person. 
 Eidolon is a Seminus demon, a sex demon that requires sex often in order to survive. And his love partner has to be satisfied in order for him to be satisfied. After a certain age, he has to be bonded to a female otherwise he will lose his mind. This age is approaching and Eidolon does not want to lose his mind. He has endured a lot to become the first demon doctor and to build the first demon hospital. 
 Underworld General Hospital aka UGH is a perfect little world. Demons -even the meanest ones- are likable or at least tolerable but definitely interesting. 
 The same way some humans can be bad and this is not accepted by humans' society, some demons can be nice and this is not accepted by demons' society. 
 The atmosphere of the series reminds me the TV series Angel, which I used to adore. Angel (David Boreanaz) was a vampire whose human soul was restored to him by gypsies as a punishment. Epic TV series! 
 Larissa Ione has created a whole new world with places, mythology, demon names and attributes. It will blow your mind if you love paranormal and you give it a chance.