18:

Ginny thought about reconciling with Luna, about somehow hinting to her that she wasn't angry with her and that everything could go back to normal, but she didn't. Instead Ginny did something so devious, and so sinful that she went to the Girl's loo afterwards and bawled. But as Ginny cried, she realized that she wasn't crying because she had wronged Luna, she was crying because she was afraid that she would be caught.

Ginny had sent Draco a note telling him to meet her in the Hufflepuff Quidditch tower on Wednesday night, two weeks after the ball. When he came she could tell that he was surprised that Luna was not there, but they had sex with out her anyways- three times, in fact. It had been rough; Draco had pulled out a chunk of her long red hair, Ginny had bit him on the abdomen and made him bleed, and both were covered in bruises. With a triumphant smile, Ginny noticed that Draco couldn't walk normally afterwards because of the pain.

The deal had been that neither would tell Luna about their little masochist romp in the tower, but Ginny had always felt that Luna had some psychic abilities when it came to that sort of thing. And she didn't want Luna to be angry at her, but she also wanted to be the one with the choice; to have Draco and Luna fighting over her.

Draco limped slightly back to his dormitory, reliving that afternoon with Ginny in his mind; he didn't know she could be so rough. The sudden thought of Ginny in leather with a whip entered his mind… he enjoyed this thought and lingered on it for the rest of his walk.
So what had happened? Did he like Ginny more than Luna now? He was sure that Luna could be just violent as Ginny, probably more so. And then Draco was filled with the thought of Luna in leather, wielding a whip.
He closed and locked his dormitory door and flung himself onto his bed. He was exhausted from Ginny, but this new thought of Luna reinvigorated certain parts of his body.
Draco smiled to himself as he undid his pants and thought of both of the girls in leather- with each other. Thankfully, he had a way of making that fantasy come true.