Draco was five when his parents sat him down and explained his Purpose.

"Your sister is different," his mother began, voice prim and proper and gentle and unyielding all in one.

Draco twisted in the armchair to look over at Leonis. His sister was standing in front of the fireplace, both hands pressed up against the metal grate Lucius had conjured there after she'd tried to crawl into the flames. She'd been standing there for . . . a while. Draco had gone outside to scare the peacocks, slid down the bannister at least a half dozen times, and even had a snack before his parents had ushered him back into the sitting room for a talk and he'd found that his sister hadn't moved.

But he also knew that Crabbe had eaten a bug the last time he'd seen him, and that seemed pretty different, too.

"She is?" he asked his mother with the absolute innocence of someone who truly didn't understand that some kinds of different were supposed to be wrong.

"Your sister is . . . sick," his mother amended carefully. "Not in a traditional way that we can manage with potions, you see. In a different way."

There was that word again, and Draco couldn't understand why they kept saying it so oddly.

"Leonis, come eat," Lucius called as Dobby appeared, left a silver tray of madeleines and sausage rolls on the cocktail table, and disappeared. "And let me check your hands."

Draco grabbed a madeleine and stuffed it in his mouth while he watched Leonis stick her tongue out at air before she skipped over to join them. She turned over six sausage rolls to examine them from all angles and babbled to no one in particular about how she liked them when they were a just a bit burnt before she eventually picked one out. Then she immediately turned away and moved to stand close to one corner of the room, facing the wall and talking loudly about cedar wood, of all things.

"So?" Draco asked, wriggling down from the chair and standing directly in front of the tray to grab another madeleine.

"She needs more help than most people," Lucius said simply. "As her older brother, it's very important that you understand your responsibility. Especially given her . . . condition."

He fixed Draco with the very serious look he only used for very serious occasions. Draco had seem him use it once when Severus was visiting and had— Oh. He'd had potions that Narcissa wanted Leonis to try, and she'd attempted to bite his fingers off in her gratitude.

"We all must mind your sister. As her flesh and blood, it is for us to care for and protect her."

Draco ate another madeleine and shuffled his feet on the rug his mother loved so much. "Me?" he asked. Narcissa was already smiling proudly, combing her fingers through his hair. Once she'd done so, he ran a hand through it to fix the way it felt like it was laying wrong. "She doesn't need that," he finally said. He couldn't imagine her really needing any special care or protection. He'd see her make her own bed even though they had house-elves for that, and last week she'd stuck his mallet to the ground with magic after he'd beaten her at croquet for the third time.

"She does," Narcissa said firmly. "Our little Leonis is very smart and independent and—"

"Annoying," Draco snorted.

She silenced him with a sharp look. "Your sister is different," she repeated. "And she needs things from us that no one else can give or should know about."

Draco huffed and sat down on his mother's favorite rug. It felt like hours that he stayed there, picking at the sausage rolls and eating more madeleines while Lucius and Narcissa explained their expectations and Leonis's needs. At the end of it all, Lucius knelt in front of him and put a firm hand on his shoulder, asking if he understood. Draco nodded even though he wasn't quite sure he did. He didn't get the details. He didn't get why he couldn't let people look at Leo too long or why he should always ask if she was hurt as if she didn't know how to report her own injuries. But he did get that, for some reason, she needed him. And because of that, he had a Purpose.

The next morning, Leonis tripped down the last four steps on the stairway because she was too busy arguing with no one about the Wronski Feint, and Draco had her take off her socks so he could check her for broken toes.

Draco was six when he lost track of Leo for the first time.

She was just Leo now, most of the time. The change had happened not long after she started waking Draco up after bedtime so they could sneak outside to stargaze. She liked to point out the constellations to him, and she'd said something about the Leo constellation's brightest star that he didn't quite understand. And then she was the one to point out that their parents probably—definitely—knew about their late night stargazing after they'd gone out one night to find a blanket and basket waiting.

But none of that mattered right now because Leo. Was. Missing.

"Maybe it was the ice cream," Draco said, floundering for an explanation. "She's always cold, and we got her something cold to eat, so maybe that's why!"

Draco didn't actually think for a minute that Leo had run off because Fortescue's cardamom ice cream was too cold.

Narcissa had already torn through seven businesses, and Lucius returned from checking the street itself and interrogating every person he could get his hands on. "I'm sorry," Draco said. Mortified, he realized he was about to cry. Six was far too old for him to be crying.

"It's not your fault," his mother said as she pulled him into a fierce hug. But her voice was shaking as she said it, and it wouldn't be shaking if he'd kept a better eye on Leo.

They searched through three more stores. Leo loved creatures, so Draco had suggested the Magical Menagerie. She wasn't there.

Narcissa was the one that said Madam Malkin, since she was one of the few in Diagon Alley that Leo saw with some semblance of frequency. Madam Malkin was the only clothier they trusted to be careful not to touch her when doing fittings. Especially after that dreadful trip to Bonnetvolant Chapellerie earlier that summer when no one had listened to their warnings (especially Draco's, and he thought he'd been rather insistent) and the apprenticing miliner had to be whisked away for treatment. Lucius had refused to pay for any of the hats that were now bloodstained from the woman's panic. But it was no good, because Leo wasn't at Madam Malkin's either.

It was Lucius that reasoned Leo's new obsession with potioneering may have driven her to the apothecary, but Mulpepper assured them that he hadn't seen her since they'd brought her there three months prior for a cauldron and her very own potion kit bag. As they stepped out on the street, Lucius anxiously said he would check Mulpepper's other location just in case. Draco watched him walk briskly away in the direction of Knockturn Alley. He didn't know much about the other alley beyond a few warnings to never—never—go there unaccompanied, and the way Narcissa gripped his hand tightly made a pit form in his stomach. Because going somewhere she was not supposed to under any circumstances was exactly the kind of thing Leo would do.

"We could call the aurors," he offered up, afraid.

Narcissa shook her head. "No, this isn't the kind of thing they do."

"Oh." He considered that. Leo had spent two full days six months ago talking about nothing but aurors and then hadn't mentioned them once since then. From everything she'd said, he couldn't imagine they'd get involved unless she'd been— No. She hadn't been kidnapped. Of course not. Leo just liked to do her best to never listen to them or stay put where he could watch her. She was annoying like that. "She chewed one of her quills until she couldn't use it anymore," he said, grasping for anything that might help.

"Again?" Narcissa asked with a gasp. It sounded like she could almost be amused if not for the fact that Leo was gone and he didn't know where—

"Maybe she's gone to get a new one." Draco stared up at his mother with pleading eyes. Maybe if he hoped hard enough, Leo would be there when they stepped into Amanuensis's.

She was not.

"I'm sorry," Draco said again, and this time he had to choke the words out. He was six, and six was too old to cry, but he definitely was anyway. Narcissa knelt down to pull him into her arms, and he found it hard to be embarrassed when he was so scared that he'd failed.

"Cissy. We've been looking for you."

Narcissa yanked back from Draco. "Andromeda," she breathed, sounding shocking and off balance for just a moment. And then, "Leonis! Darling, we were so worried!"

Leo was standing there, looking completely unbothered while leafing through an unfamiliar red book. The cover was embossed with gold and read Sonnets of a Sorcerer. She was next to a tall, stiff woman that looked both an awful lot and an awful not like the few pictures of Aunt Bellatrix that he'd seen.

But he didn't really care about her.

"Where were you?" he hissed at Leo, stepping over to her and ignoring the tense conversation he could feel the two women having above them. When she didn't answer him, he snatched the book from her. "Idiot!"

Leo finally looked at him as if she hadn't even realized that they'd been reunited. "Oh, Draco. May I have my book back? I've just met Aunt Andromeda, and she bought it for me in exchange for me coming with her."

"Where did you go?"

"Flourish and Blotts," she said as if it was obvious.

"We looked in Flourish and Blotts," he countered. "You weren't there."

"I probably wasn't, yet," she conceded. "I was at The Junk Shop first. In case they had anything fun."

"Anything fun?" he asked carefully. "You left to find something fun?"

She nodded, plucking her book from his hands and looking through it to find her page again. "Like that stick we saw the Muggle on."

Draco wrinkled his nose, thinking back to the odd contraption they'd seen an older child using. It bounced, and the kid had fallen and gotten hurt more than once. He didn't quite see the appeal. "I'll get you one," he promised. "If that will keep you from disappearing again." He'd just have to get one of the elves to put a cushioning charm on it; he wasn't sure how Narcissa or Lucius would react to him getting Leo a Muggle toy, even if it was to keep her safe like they'd asked him to.

"Will you?" Leo asked, eyes wide. She closed her book. "Do you think it will be like using my broom?"

He doubted it. It was a Muggle device, after all, and he told her as much. It didn't seem to deter her, and her attention was soon refocused as Andromeda finally left—she seemed to do it in quite a huff, too, and Narcissa looked less than pleased by whatever discussion they'd had.

Their mother knelt in front of Leo and looked her over with a sad smile. "There you are," she whispered. "Let's go find your father."

Draco was seven when he realized how many secrets he was keeping for his sister.

In fact, it was the day he turned seven that he realized it, sitting on the floor of her bedroom and watching as she opened a present from an unknown owl that had nothing but her name on it. When the last of the paper the gift had been wrapped in fell away, Draco stared at the book's title. Home Life and Social Habits of British Muggles. Well, he definitely couldn't tell mother or father about that, could he?

So instead, he settled for scoffing and grabbing the paper. "I didn't think you knew how to read." He balled up the paper and then nailed her in the head with it.

Leo stuck her tongue out at him and decided then would be the perfect time to explain that she'd started working on the pumpkin-head jinx. She wasn't quite confident with it yet and wanted some more practice. She got as far as Melo in the incantation before Draco yanked all the blankets off her bed to bury her in. He'd learned that enough layers between them meant touching her wouldn't hurt too much too fast, and he hadn't told her his plan of slowly building up a tolerance because he knew she'd say no.

In the end, she did manage to hit him with the jinx. Then she giggled while calling Dobby and asking him to undo what she'd done. Draco watched the way she grinned at the house-elf and thanked him so sincerely.

Yes, that was another secret he was never sharing. Right alongside the magic itself, which she never seemed to do in front of their parents for whatever reason. And right alongside how many times he'd snuck in her room and stayed in her armchair while she slept because he'd heard her screaming.

Draco was eight when he had to reconsider what protecting Leo was supposed to look like.

"You don't even have a brain," he told her as they stared down at the tipped cauldron and spilled quodpot solution. "You're dumb. Let me see your hands."

She grinned and held up her hands, balancing on the broom with her knees. It was hard for him to properly see her palms with the way she was still flying a good nine or ten feet above them, and Draco scowled at her. Part of him wanted her to suffer the consequences of her own stupidity for wanting to try an awful game like this, but he couldn't deny that he hadn't liked the way the quod had exploded while she was still holding it. It didn't help that Goyle and Crabbe were still on their own brooms, snickering.

"Get down here," he finally said. "Try not to crash; you've done enough damage already."

Leo just laughed and swung off the broom while it was still lowering. She dropped the majority of the way, and Draco's heart leapt into his throat and decided to live there. She just rolled as she hit the ground and then sprawled out in the grass, staring up at the sky with wide eyes as if she'd never seen it before. "Oh, shush," she said, waving a hand. "I'm having fun. The books will still be there when I'm done."

Draco swallowed forcefully and huffed. "Hands," he reminded her.

"Who are you talking to?" Goyle asked.

Instead of doing what Draco had directed, Leo rolled onto her stomach and squinted up at Goyle. Then she squinted at nothing. Then at Goyle again. Draco glanced between the two of them nervously, trying to figure out how to remind Goyle not to break the rule about pointing out her talking to no one in a way that would keep him, Draco, from acknowledging that she'd been talking to no one. Again.

"Just Merlin," Leo informed him.

Then she stretched her arms out in front of her, the backs of her hands against the grass. Palms up. Draco could see the mild burns left from the quod. He sighed and opened his mouth to call Dobby.

"You are crazy!" Goyle said, laughing. "My dad was right. You're barking!"

Draco scowled. Yes, Leo probably was insane, but—

"Entomorphis," Leo said from her spot on the ground. She said it as if she was commenting on the weather and not casting a wandless spell he'd watched her spend months practicing.

Goyle screamed at first. He didn't stop screaming, exactly, but the screaming did morph into squeaking as he started to hunch over and feelers sprouted from his forehead. Crabbe screamed, too, and ran inside.

Leo sat up and looked down at her hands. "Oh! Looks like I fixed myself up." She held her hands up to show off her healed palms, but she was trying to show the empty air and not Draco, so he decided not to comment on it.

Draco was nine when he failed. Horribly. Miserably.

He spent a week and a half begging his parents for forgiveness they insisted they didn't need to give despite the fact that Leo was gone, he had no idea where she was, and he didn't even know where to start looking. It wasn't like when she was six and had wandered off in Diagon Alley. No, this time, they had all woken up to a house that didn't have her inside it. She'd vanished from inside their home, and Draco kept trying to understand why. He kept her secrets, he got her the things she wanted, and—despite his best efforts—she hadn't lost a game involving a broom in years.

And then she was back.

Draco had been angry with Leo before. She had a terrible habit of keeping his things in place with sticking charms when she was upset with him or sometimes just when she was bored. She liked to practice hexes and jinxes on him whether he liked it or not, regardless of if he was doing something already or wanted to be left alone. And he could count more than a few times when she'd done something she wasn't supposed to—a broken vase here or a stolen wand there—and pinned it on him despite his protests.

But this? He'd never been angry with her like this before. He felt like his insides were boiling. When he saw Leo standing in the parlor as if she'd done nothing wrong, he wanted to yell at her and throw things until she cried as much as Narcissa had. Instead, he had stormed up to his room and screamed into his pillow until his throat was sore.

Narcissa knocked at his door and let herself in. "You didn't come down for dinner," she said with a smile, setting a plate and glass on his nightstand.

Draco sat up and rubbed at his eyes. He stared at the plate for a long moment before shuffling to the edge of his bed. He sniffed and didn't move to pick up the fork.

"What is it?" Narcissa asked softly, brushing his hair back from his forehead.

"Why aren't you mad?" he whispered. "What she did was awful. I thought she might be dead."

She paused for just a second before she sat beside him and started rubbing circles on his back. "Your sister is different," she began.

"Yeah, I know," he spat. "I know."

"With her, we need to choose our battles wisely. Your father caught her trying to sneak out, once. Last year. She spent the next week reading so intensely that she wouldn't eat. Wouldn't sleep. Wouldn't do anything. You remember, don't you?"

Draco did remember. He hadn't much cared for that week.

"She came home, mon étoile," Narcissa cooed, touching his chin so he would look at her. "She came home. We didn't know when she left, and we couldn't stop her. But she's here, now."

"So it doesn't matter?" he croaked. "It doesn't matter that she was gone?"

"Of course it matters. Do not think for a second," —her grip on his chin tightened, and there was a fire in her eyes— "that your father and I aren't trying to figure out why she left or where she went. But doesn't it matter more that she's home?"

He sniffed. He hadn't liked that one week, but he'd liked it more than this past one and a half. So he nodded and let Narcissa pull him into his arms. He wasn't going to cry again. He just wanted to be held. Just for a little while.

That night, Draco snuck into her room. Just to make sure she was actually home. Just to see if he could hold her, too. She'd never gotten to be held; he wondered if she wanted it.

Draco was ten when he realized he would never understand Leo.

Pollux Black was dead. They were at his funeral, and Leo spent it nodding at nothing, hand occasionally reaching out to hold something that wasn't there. At one point, she said, "Really? What did they do to him?"

Draco kicked her to shut her up. He'd learned a while ago that he'd be fine if he did it quick enough and was wearing shoes.

Leo glanced at him askance before shrugging and leaning back in her seat to stare at the ceiling for the rest of the ceremony. The ceiling was charmed to look like the night sky, the Gemini constellation taking up most of the room, so it made sense that she would like looking at it.

After it was over and they were all standing, Cygnus Black III came to speak to the only daughter he had there. Draco thought he looked much older than fifty-two, but it was Leo who put it into words by leaning over to empty air and whispering, "He looks quite ready to follow his father, doesn't he?"

"Leonis," Narcissa gasped reprovingly.

Leo blinked as if she was just then remembering there were people in earshot besides herself.

Cygnus frowned as he stared at her. "Ah, yes," he said slowly. "I . . . forgot about this one." He cut his stare to Draco. "Do us proud. You have," —he very much didn't look back at Leo— "certain blemishes to make up for. But there is strong blood in you; you'll manage, I'm sure."

"Oh, that's me," Leo mused. "I'm the blemish."

Draco was eleven when he saw Leo hit the ground.

The bludger was already zooming away to find another victim, and Draco distantly and uselessly tried to piece together which Weasley twin had hit it before he resolved to be furious with them both.

He wasn't sure he breathed in the time it took him to get from the stands to hospital wing, and he was gasping for air when he burst inside. He stared at the bed Leo was in. Madam Pomfrey and Severus Snape were gathered beside her.

"Is she dead?" he asked rather dumbly.

"No, Mister Malfoy, she is not," Madam Pomfrey assured him. "It was a nasty hit, but she'll be quite alright."

He stood there, not for the first time feeling like his caretaking and protecting abilities were quite lacking.

After a minute, Madam Pomfrey looked up at him again. She softened. "Mister Malfoy, I'll have these bones set right shortly, and then all she'll need is rest. Perhaps you could bring something to occupy her during that time."

He nodded and backed from the wing. He couldn't get to her trunk in her dormitory, but he was sure he could dig up a book or two in the library she hadn't found yet.