Throne in the Dark by A. K. Caggiano

For fans of Kimberly Lemming and The Princess Bride comes the first book in AK Caggiano's Villains & Virtues series, following the son of a demon on his way to fulfill his dark legacy, and the blonde pickpocket he accidentally magically links to him along the way.

Dark lord, demon spawn, prophesied realm destroyer.
With a demon for a father, Damien Maleficus Bloodthorne's destiny could be nothing short of nefarious. On the cusp of fulfilling the evil inevitability his dark life has led to, all it will take to solidify world domination is the completion of his most vicious spell yet. 

But then, her. Bubbly, obnoxious, blonde. 
Harboring secrets of her own, a tiny yet troublesome thief calling herself Amma completely upsets Damien's malevolent plans when she mistakenly gets chained to his side through magic. Forced to drag her across the realm on his unholycrusade, Damien knows that killing her would fix things, of course, but the nauseatingly sweet Amma somehow begins to prove herself useful. And worse yet, she then proves herself the source of something even more sinister: feelings. 

Torn between his villainous birthright and the virtue Amma insists on inspiring, Damien will have to decide if he will help the tender thorn in his side or cut it out at the heart.