When Bellatrix left for Hogwarts, Andromeda cried more than the rest of her family put together. The night before, she had hung desperately onto her sister, begging her not to leave.

"I have to, Andi," Bellatrix had told her. "I've got to go to Hogwarts."

"But why?" Andromeda sobbed, clutching the front of her sister's dress. "I don't want you to go! Please don't, Bella, I don't want to stay here all alone!"

"Stop it," Bellatrix told her, which caused Andromeda to break down into still harder tears.

"B- Bella… I'm scared for you to go," she whimpered. "Mummy and Daddy don't like me the way they like you and Narcissa… I'm going to go crazy locked up here all alone!"

"No you're not," Bellatrix said very firmly. "You're going to be fine, I promise."

"I'm not!"

"Yes!" Bellatrix lost patience with her sister. "Yes, you are going to be fine, I promise you. Mother and Father love you," she added, though she sounded a little as though she didn't entirely believe herself when she said it.

"No they don't," Andromeda sniffed. "They don't even pay attention to me except to tell me I'm not being ladylike."

"We both know that's not true," said Bellatrix. "You're Father's favourite, everyone can see it. Everyone except you, it seems like!"

"I am not. Narcissa is his favourite, she's everyone's favourite. She's the perfect little princess, we all know that."

Bellatrix sighed, then touched her sister's cheek, sitting down on her bed and pulling her sister up into her lap.

"Do you know where the name 'Andromeda' comes from?" she asked, smoothing her thumb over her sister's soft skin.

"No," said Andromeda, voice trembling as she sniffed and Bellatrix wiped the tears that had fallen down her cheeks.

"It was a princess," Bellatrix told her. "Andromeda was a princess in Greek mythology. She married Perseus."

Andromeda managed to smile, feeling much better for being told that. "Really? I'm named after a princess? Shouldn't Narcissa be the one named after a princess?"

"No," Bellatrix said, smirking slightly. "Narcissa is named after a boy from Greek mythology who fell in love with his own reflection and died. Your name is a lot better than Narcissa's. Mother and Father must think you're a princess to give you a name like that."

Andromeda's smile widened and she felt a little well of comfort in her stomach. "Oh… do you really think so?"

"I know they did," Bellatrix said with utter conviction. "Now," she added, "do you want to sleep in my bed with me one more time before I leave?"

Andromeda nodded. Bellatrix stood up and pulled Andromeda to her feet as well, turning her around to undo her dress.

Andromeda had just recently been started to wear corsets – at their mother's insistence – and she still did not have any idea how to get herself out of them. Bellatrix's skilled fingers worked the buttons on the back of the dress open, letting it fall around Andromeda's ankles, leaving her in just her underskirt and corset. She leaned down, her hair tickling the skin of the backs of Andromeda's shoulders as she squinted to see the laces holding the corset together in the dim light of their one lamp. Andromeda bit her lip to stop herself from laughing at the tickle, and she could feel goose pimples rising along the back of her neck and arms.

Bellatrix made a soft, "Aha," noise, then jerked on one of the laces and Andromeda felt the strings release. She took a deep breath, causing the corset to pull apart a little. Bellatrix's cold fingers skimmed along her skin, and Andromeda shivered involuntarily.

"All right?" Bellatrix asked, finishing loosening the strings and raising Andromeda's arms above her head so she could pull the corset off that way instead of having to unlace it all the way.

"Yes," Andromeda said softly as the garment was pulled off her. There were red marks in her skin where the boning had been pressed in too closely. She rubbed her hands over her flesh, trying to get rid of the marks.

"Here, let me," said Bellatrix quietly, setting the corset aside. Her hands moved over Andromeda's sides and back, gently rubbing and kneading the flesh. Andromeda shivered a little. At only nine years old, her figure was still childlike, and the corset had dug deep creases into her waist, trying to force it into an hourglass shape.

Bellatrix sighed as Andromeda winced. "You'll have bruises in the morning… honestly… tell mother not to lace it up so tightly. You'll get scars."

"Scars?" Andromeda asked, horrified by the thought. She had never been scarred, and the very thought of permanent marks marring her flesh terrified her.

"Don't worry, though," Bellatrix said quickly. "As long as you just keep the corset a little looser, you'll be all right, I promise." Her hands were on Andromeda's stomach now, slowly rubbing away the red marks.

"Stop," Andromeda said, pushing her sister's hands away.

"What?"

She crossed her arms uncomfortably over her chest, and Bellatrix let out a small Oh sound. "Self-conscious?"

Andromeda shrugged, blushing as she looked down.

"Well," Bellatrix said, "I'm your sister. You don't need to be self-conscious around me. And you don't want scars on your chest now, do you?"

Shivering, Andromeda shook her head. "N- no…"

"Then you'll let me make sure the corset boning isn't going to leave marks all over your breasts," Bellatrix said simply, taking Andromeda's hands off her breasts.

Andromeda flushed, her cheeks going deep red. She looked down, her hair falling over her face to hide it for shame. Over the summer, she had finally started to develop something reminiscent of a bust. Two small, soft, rather ungraceful bumps had grown on her chest, and much as she hated her corset, Andromeda was glad at least that it hid her breasts from view.

Bellatrix didn't touch her, but Andromeda felt her eyes, then Bellatrix said, "You're fine. No scars there."

Andromeda looked up to see her older sister turning away and shrugging out of her own dress and letting it fall to the ground around her ankles. "Would you undo my corset, Andromeda?"

Childish hands trembling a little, Andromeda set to work on her sister's corset strings. She tugged rather clumsily at them, causing Bellatrix to gasp in pain when her rib cage was compressed still further as Andromeda accidently pulled the laces tighter.

"Sorry," she mumbled, finally managing to get the knot undone.

"It's all right," Bellatrix said, gasping for air as Andromeda loosened the garment. At last, she managed to wriggle out of it, and she rubbed her hands over her own sides, back and front to get rid of the marks.

The two girls stood, in only their underskirts, looking at each other for a moment. Bellatrix looked, in Andromeda's estimation, much older than eleven – thirteen or fourteen at least. She stood tall, seemingly proud of her body in a way that Andromeda never could be.

Bellatrix glanced in a mirror, twisting around to be sure that there weren't any serious marks on her skin, then nodded in satisfaction, letting her underskirt slide down her legs and pulling on a nightdress. Andromeda did the same, though unlike Bellatrix, she did her best to hide herself modestly.

"Now, come on, Andi…" Bellatrix said. She pulled back the covers to her bed and crawled in, and Andromeda followed.

"You have to be a good sister to Narcissa while I'm away, all right?" Bellatrix said, pulling the blankets up over them. "You have to make sure she has a good big sister who will help her and love her and all that…"

"I'll be as good a big sister to her as you are to me…" Andromeda told her. "Or… I'll try at least. No one could really be as good a big sister as you."

Bellatrix let out a short, harsh laugh. "Is that what you think?"

"Yes," said Andromeda, without even a shred of hesitation.

Bellatrix sighed and shook her head. "You're wrong, Andi. I'm not a good big sister. I'm a very, very bad big sister."

"No you're not!" Andromeda was outraged at the very suggestion. "You're the best big sister in the word! You're… you're always nice to me and you let me sleep in your bed and everything…"

"I know," said Bellatrix. "That's what makes me a bad big sister."

"I don't understand…"

"Good big sisters," Bellatrix told Andromeda, "do not let their little sisters sleep in bed with them."

"Why not?"

"Because it's wrong."

"Why?"

"I don't know," Bellatrix admitted. "But Mother says it's wrong. She told me I'm not supposed to let you sleep in bed with me." She shrugged her shoulders. "I'm still going to, though. It's not as if Mother will ever know I did, as long as you don't tell her."

"It can't be wrong to let me sleep in bed with you…" Andromeda frowned a little as she considered. "Things are only wrong if they hurt people, aren't they? We aren't hurting anyone by sleeping in the same bed, are we?"

"That's what I think too," Bellatrix agreed. "But Mother says it's wrong, and I'm a bad big sister for doing it."

Andromeda spent a long time contemplating that. Was Bellatrix a bad big sister? No, she couldn't be. Andromeda was only ever happy when she was around Bellatrix, and that had to be the mark of a good big sister.

Before she fell asleep, Andromeda had already decided beyond any shadow of doubt that no matter what her mother said about Bellatrix, Bellatrix was the best sister in the world, and Andromeda would be just as good a sister to Narcissa.

Even though she didn't like her.