Sabin:Demon of Doubt 
 Butterfly: on right rib cage and waist 
 His curse: His demon creates insecurities to everyone including unfortunate Sabin. His self-doubts do not let him be happy and they make him constantly miserable. Fighting and killing is his only pleasure. 
 Gwen Skyhawk or Gwendolyn the Timid:Harpy 
 Supernatural ability: She is an immortal (although for the time being is only 27 years old) and very strong (although she does not particularly crave violence). The great mystery is who Gwen's father is. She thinks that he is an angel. (view spoiler)[(We will learn that he is Galen, the Lord of False Hope.) (hide spoiler)] 
 Sabin is the co-leader of the Lords of the Underworld with Lucien. His demon of Doubt is his strongest weapon. He whispers words of insecurities and creates strong emotions of self-doubt. Most of his enemies commit suicide when they listen at the whispers for a long time. 
 Moreover his last lover, Darla, had killed herself because of the voices and he'd vowed not to get involved again. And then one day he meets Gwen. And he wants her. And Doubt wants her, too. 
 "I want her." 
 "I want her, too", Doubt piped up. 
 "You can't have her". Which meant he couldn't either. "Remember Darla? As strong and confident as she was, you still managed to break her down." 
 Gleeful laughter. "I know. Wasn't it fun?" 
 His hands fisted at his sides. Fucking demon. 
 Gwen was imprisoned by Hunters for a year, until Sabin and the Lords saved her. Sabin really desires to keep her, but the rest of the Lords insist that she has to leave. Because surprisingly they are scared of her. 
 This time we learn about female beings stronger than the Lords. The Harpies: Gwen and her sisters Bianka, Taliyah and Kaia. 
 "The woman was going to kill him, and not because she was stronger and more vicious than he was. Which, if he thought about it, she was. He'd never ripped a man's throat out with his teeth, and he was damned impressed that Gwen had. She'd made the Lords of the Underworld look like marshmallows." 
 Gwen will be strong enough to defeat all the doubts (I honestly wanted to shout at Doubt sometimes as well "Oh shut up") and the love between Sabin and Gwen will grow stronger and stronger. 
 "I can't believe I resisted you, even for a second." 
 "More." 
 "Have I told you yet how beautiful you are? How much I love you?" 
 "More!" 
 It is so sweet and so right the way each of the lonely immortal warriors is mated and he finds happiness.