"She rapes her brother...
Her brother is one hot guy.
His sister though has trouble finding a decent boyfriend.
So she wants to seduce him, but he refuses as any (average) boy would. I think.
His girlfriend wants him to stay a virgin till they marry. They don't have sex. He's horny as hell but doesn't masturbate, has plenty of wet dreams, the works. (These guys still do exist, but are hard to find.)
His sister knows her brother is loaded with cum and doesn't get a good release once a while.
One night he's at home alone with her. She maneuvres him into a blackmail situation.
He has to undress but keeps his speedos.
She ties him to the bed, blindfolds him. She admires his gorgeous body and tries to excite him with her fingers, feathers, babyoil, etc.
He gets an erection, is ashamed. He struggles to get free. Useless. The teasing goes on for some time, he's wet with precum. He has to lick her pussy.
She finally grabs his hard cock and slides it in her. She rides him.
He cums quickly, and is forced to cum again and again.
The bitch sis taped the whole session on video!
He's in for more sick action. Or else...