Aeron:Demon of Wrath 
 Butterfly: in the middle of his back. (Although he kind of likes tattoos. He has several others.) 
 His curse: He craves violence. His Demon senses the sins of anyone nearby and forces Aeron to attack and to punish - no matter how small or big the sins are, no matter if there is a good reason for them or not. 
 Olivia:warrior angel 
 Supernatural ability: She used to be an angel, so she had a number of abilities including creating weapons from air, shielding herself from the world's evil and flying with two amazing wings. Unfortunately, her wings were removed violently from her when she decided to become fallen in order to be with Aeron. 
 Aeron is a bad boy with tattoos and piercings. Oh, and he has wings. Black ones. He is another tortured Lord who likes torturing. Aeron owns a big favor to Paris, the Lord of Promiscuity. Because Paris has chosen to save his best friend instead of finally being with the love of his life, Sienna. 
 Aeron is lonely. He has of course Legion, but she is really a demon minion and not that trustworthy. And then he meets Olivia an angel who was trying to kill him, but then she fell in love with him. And now she is no angel any more. More precisely she is weaker than a human now and totally in Aeron's mercy. 
 "What are you doing here, Olivia?" 
 "I'm here...I'm here for you." 
 The way Olivia has lost her wings in order to be with Aaron, it kind of reminds me the fairytale of The Little Mermaid who lost her tail in order to be with her prince. 
 Olivia believes in Aeron. She became fallen for him, weak and easy to kill. Just because... 
 "Because you aren't what you believe you are. You aren't what everyone else believes. You might have delivered countless deaths but you love more fiercely than anyone I've ever known. You give of yourself with no thoughts to your own happiness." 
 Most women love bad boys and tortured heroes. Fortunately, Aeron will love Olivia back. He will love her more fiercely and more passionately than Olivia would hope. 
 I just love Aeron and Olivia together! I cannot really decide who made the biggest sacrifices for the other. 
 Final note: The book also starts the love story of Galen (the Demon of false hope) and Legion. Their HEA is one of the books I am looking forward to reading hopefully soon :) 
 "Kiss me," he commanded. 
 "No." 
 "Kiss." 
 "No!" 
 "Why not? Not like it's anything special." 
 "Cease...talking!" she growled. 
 His snarl was like a caress. "Fine. You want a quick fuck, that's all you'll get." 
 8 books and 7 years after this one-night stand Galen cannot stop thinking of Legion.