Narcissa is afraid of the dark.
Her room is five doors away from Ana's and two away from Bella's. Narcissa is scared of Bella too, and sometimes when she is all alone in her bed, Narcissa thinks she can hear Bellatrix slipping quietly through the corridors. Bellatrix isn't afraid of the dark because she is tall and strong and the dark wouldn't dare to touch her.
Narcissa imagines that Bellatrix likes to eat up the dark. In her dreams, Bella eats so much darkness that it fills her to the brim; then it spills out into her eyes and her hair and turns them pitch black just like she is on the inside, where no one can see it.
Narcissa isn't scared of Ana. When Narcissa was little, Andromeda would tell her stories before bedtime. They were good stories. Andromeda would stroke her hair until she fell asleep, her hands gentle and soft. Narcissa never had nightmares then.
Andromeda is gentle and quiet and always, always kind. She's older than Narcissa and younger than Bellatrix and cleverer than both of them. Narcissa wishes she could be more like Andromeda, but she is only pretty and afraid, and very small. Andromeda isn't any of these things. Neither is Bellatrix, but Narcissa doesn't want to be Bella's shadow.
She would not mind being Andromeda's shadow. Andromeda, who does not creep through the house at night. Andromeda, who does not dream of darker things. Her sister, who once whispered stories of light and love, as if she believed them. If Narcissa was Ana's shadow, she would not see the darkness, because Ana has always been numb to the dark pouring through her own veins.
One day Narcissa will close her eyes too, and then the darkness will come and swallow her up.