Fleur Delacour is a sadist. She enjoys twisting and pulling and bending people until they snap, until they break. Then she likes to pick up the broken pieces and bind them all back together again inside-out. For her, there is nothing better than the satisfaction of making a monster, and then seeing that monster fall.
As soon as she saw him, she knew that she wanted to do that to Harry. And she did. But no matter what she tried, no matter how hard she pushed, no matter how isolated, liberated, and depraved she made him, he just wouldn't break. Her friends, usually just as cruel as she was, started getting worried. They told she'd done enough, then too much, then they stopped talking to her all together. It didn't matter, they didn't understand. She was running out of time, our chances. She had until the third task to break him and she was obsessed. Her best friend left her the day before, she spent that night with her toy, compulsively playing and twisting. He was barely human by then, but he still didn't break. She'd explored the depths of magic with him, he her test subject for all the things she'd never dared to try, and even more.
Things he had discovered, leaps he had made off of what she taught him, things so twisted and vile she hadn't even known they could be real, and it was rapturous. But no matter what she did, no matter what she convinced him to do to himself, he never broke. The third task came and went, and he disappeared. She failed, and she left Scotland feeling hollow. She wandered listlessly through the last of her days at Beauxbatons, and wandered more through her own home. Her parents didn't know, didn't understand. Maybe her friends had been right. She'd gone too far, gotten too involved, she gave as much as she took and she couldn't get it back.
SHE WANTED IT BACK!
Then, one night, she woke up to a breeze across her face and chest. A shadow stood at the foot of her bed. A horrible, skeletal monster. It's body was half dead, ligaments torn and muscles flayed. Flesh burned and blood seared. Bones, hardened to steel, blackened and scorched, and everywhere the rot and web of decay. But it was only half dead. The eyes, bulging and pale, were fixed on her. The breath, ragged and heaving, moved in time to her own. The voice, horribly warped, familiar as her own.
"I will not leave you, never again."
Harry Potter strode forward and took one of her perfect hands in his, her unbroken creation. It smiled and, in her own mind, Fleur screamed.