Narcissa watches when Bellatrix thinks she’s asleep. She watches her kick the covers off and remove all of her clothing. She watches her claw at her breasts and bury her fingers between her legs. She watches her hips jerk and her mouth open wide enough so that Narcissa thinks her jaw is going to fall off. And she watches her go back to bed as if nothing had happened. So Narcissa rolls over and tries to forget what she’s seen.

But time goes on and that gets harder to do. One night Narcissa tries to mimic Bellatrix’s movement because she can’t stand her own heat. But Narcissa has never done this before and finds it painful. She cries out.

Narcissa watches Bellatrix turn to face her, a cruel smile curving onto her face as if she always knew of her little eyes peering into the dark. She watches as Bellatrix walks towards the bed and pulls her covers off. She watches as Bellatrix takes off her clothes and climbs on to the bed. But her eyes are closed when Bellatrix bites the tip of her breast and shoves three fingers inside her little sister.

Narcissa almost shouts, but Bellatrix covers her mouth. Her back is arching and her body is twisting and Bellatrix is making it hurt but she does not open her eyes. She merely moans and pants and listens as Bellatrix laughs at her and calls her a little whore, scraping her fingernails across her clit.

Narcissa decides it is a very good thing that Andromeda could sleep through her own death and screams into her sister’s palm when Bellatrix makes her come.