Vampire!Harry, who's not too good at the whole 'being a scary vampire' thing. One day, he attacks a French Noblewoman, one Fleur Delacour. He overpowers her easily, as you do, and as he's draining her blood, instead of being terrified that she's going to die, she's more annoyed he's staining her dress. Harry is confused. sure, he's not great at being scary, but he expected at least some existential terror. She tells him its really hard to be scared when he's being so messy and that its disgusting, and she's going to stick with him until he learns how to feed more elegantly.
[Optional: Turns out she's been reading a lot of romanticized vampire works, and has been dreaming of being assaulted by a sexy vampire and him being taken by her, spiriting her away to marry him. Harry fits the sexy part fine, but he's not elegant or dashing enough for her tastes.... yet]