They offered Draco a bed for the night and he accepted, so when Ginny wandered downstairs at arse o'clock the next morning to find something to feed the bottomless pit known has her firstborn son, she found a Malfoy making coffee in her kitchen and chatting with Phineas Nigellus, who'd taken to hovering around when there was cooking going on.

"Harry's gone to fix up a room for Hermione to stay in when we get her out," Ginny murmured as Draco set down a cup in front of her and, after a glance at James, started rooting in the cupboards for the porridge. "I told him to empty out one of the spare bedrooms and transfigure it a restful colour – I think he decided on cream – and just put in the absolute basics."

"Makes sense. After spending Merlin knows how long in that cell, she's going to have to ease back into the world. You don't think a bed might be too much at first?" Draco pushed a bowl of porridge over at her, and she started levitating the spoon to feed the baby.

"Harry and I spoke a bit last night," she said quietly. "We think she's been in there about eighteen months."

Malfoy choked on his coffee.

"What?"

"She left Hogwarts the morning after the battle, and she was gone for about a week, he said. Came back in time for Fred's funeral. Harry says he remembers her saying she was going to go back to sit her NEWTS properly before going to uni. Then she was gone for about two weeks, and when she came back she got engaged to Ron straight away, took the honorary NEWTS, and went to uni." Ginny took a slow, deep breath, trying not to think about the fact that Hermione, the real Hermione, had been missing for almost two years, and nobody had even noticed. And all for Snape? Merlin knew the man was a hero, but who would suffer that long, that much, for Snape?

Draco sucked a breath between his teeth and scowled into his cup.

"I think you're right. I spoke to her, and she said…she said she needed time, that every time she saw me she saw Aunt Bella, but she said she still loved me, that she just needed time. And then later…I saw her in Diagon Alley and she looked at me like she hated me. I've tried to speak to her but it's like she doesn't even know me anymore."

They shared a long look. Two weeks was enough to create a convincing doppelganger, if you had someone of the right gender available to Obliviate, and were skilled enough with the potions and transfigurations that would turn one person's body into another. It was the oldest, the darkest of magics. As Healers, they were taught ways to distinguish the real person from the doppelganger, and to discover the original identity of the fake, but could Ginny face the consequences of telling her brother that his wife was not who he thought she was?

"And you thought it was because of what happened at the Manor? That she couldn't forgive you?" Ginny asked gently. She sympathized with Draco, of course, but really she was trying not to wonder who was really married to her brother, trying not to go through the lists of the missing and the dead, wondering which of them had been changed into an ersatz Hermione Granger – one with worse marks, a new love for Quidditch, and a deep devotion to Ron.

Draco shrugged.

"Stupid, isn't it? I called her a filthy Mudblood in second year and she forgave me for that, and I thought she couldn't forgive me for not being able to stop Bellatrix." He snickered a bit. "God, but she yelled at me about calling her that. I thought my ears were going to catch fire. And then she sicced Severus on me, and I literally thought I was going to die."

"You're going to have to explain the situation with you and Hermione and Snape at some point, you know," Harry said mildly as he entered the kitchen. "Gin, the room is ready, so as soon as we're done talking we can take James to your mum's and start planning." He pushed his glasses up his nose, a sure sign that he was uncomfortable. "Also I don't think we should tell Ron. He's…well, he's not all that stable, after everything, and if he knows about this…"

Draco scowled.

"And I can't believe you lot ever thought she'd marry Weasley. No offense, Ginny, but…"

"He's been her best friend for seven years, Malfoy, and she adores him." Harry's voice was flat and hard, and Ginny tried not to sigh. It was ridiculous, how important it was to him that Ron and Hermione be happy together.

Malfoy shrugged and sipped his coffee.

"Look, just tell us the long story, please?" Ginny finally said. "Seriously, all through school we thought you hated Hermione, and now you're acting all concerned and like you know her, so we'd really like to know what's going on."

Malfoy sighed and pushed to his feet, pacing the length of the kitchen table, while Harry took a wary seat next to Ginny.

"Okay, so. The story goes back almost thirty years ago, before any of us were born, and I'll tell it to you like we heard it. My father had just joined the Dark Lord at my grandfather's behest. Unfortunately old Abraxas was mad, but not stupid, so the family fortune was locked up like a nun's knickers. The Dark Lord expressed his disapproval. Vigorously. Lucius was trying to apparate home, and he splinched. You think he carries that cane for shits and giggles, Potter, but he completely fucked his leg. Lost about half the actual muscle, and cracked every bone in his foot when he fell twelve feet onto asphalt."

"Merlin," Ginny breathed. "How did he survive?"

"He landed right in front of someone's car. A Muggle man, not much older than my father. Recently arrived from Israel, a dentist. I trust you can see where I'm going with this?"

"Hermione's father saved your father's life?"

"Well, yes. But it's more complicated than that. Because obviously, being Muggles, they had no way to contact anyone in the wizarding world. So they healed him up themselves. It took weeks, and the culture shock was…well, it was massive. My dad had never actually met any Muggles before, you see, and Aaron and Chani were such wonderful people…by the time he was well enough to send for my mother, they were fast friends, and he owed them a life debt besides." Malfoy paused, rubbing a thoughtful hand across his face. "This is where it gets tricky. So Aaron and Chani and Lucius and Narcissa become very close. Aaron suspects there's something different about their friend, but they never actually say anything. And then one day, Aaron comes to my father, who is his closest friend – Hermione comes by her awkwardness naturally, I assure you, and her tendency to glom onto people and stick like glue is all Chani – and he tells him that he and Chani have talked, and they would like Lucius to help them have a baby."

Harry choked on his coffee and glared at Draco, while Ginny, feeling as though she was in shock, let James squirm down and crawl off. Kreacher would keep an eye on him.

"If you're trying to tell me that Hermione is your half-sister, Malfoy," Harry growled, and Malfoy snorted.

"More like a quarter-sister. If you'd let me explain? So my father takes the proposal back to my mother, who is a very clever woman indeed, and she tells him that there should be no reason why they can't try and help the Grangers conceive their own child with magic. Especially considering a young protégé of Lucius' who is just about to leave Hogwarts, and might be willing to do a favour for an old friend on the down-low. Who happens to be a complete fucking genius at Potions, and has been apprenticing under Madam Pomfrey as preparation for his Mastery. So they ask Snape to take a look at the situation."

"I see where you're going," Ginny breathed. "Did he brew them the Patres Duos?"

"Right in one, Madam Potter," Draco said with an almost manic cheer. "Turns out that Aaron, being a Muggle, can't empower a conception potion by himself. But Snape ran the numbers and he thought that it would probably work if they brewed Patres Duos using Aaron's blood and my father's…yes, well. And so there you have it. Hermione is my father's half-daughter, and my quarter-sister."

"And I assume Snape became friends with the Grangers as well," Harry said.

"Sort of. He delivered me and Hermione, of course – Chani and Narcissa bonded while they were pregnant, and in the end I was born in the Grangers' guest room because my mother was too scared of bloody Bellatrix to remain in the house. And so they kept inviting him back. Birthdays, Passover, you name it. And little Hermione adored him. My mother said she used to stop crying when he came into a room. And when she was nine, she told him, very seriously, that he had better not marry anyone before she was all grown up, because he should give her a chance to see if he liked her."

"Aww," Ginny said with an embarrassed little grin, remembering her own childhood crush. "That's actually kind of sweet."

"Yeah, only Hermione still loves him. She never stopped. I mean, she wasn't annoying about it or anything, it was just like…I don't know, Ginevra, it's weird. It's like a fact of the universe. Water is wet, the sky is blue, and Hermione loves Severus."

"But he was awful to her!" Harry cried.

"Believe it or not, he discussed the situation with her before she went to Hogwarts. He sat both of us down and told us that the Hat would probably not put Hermione in Slytherin, because she's a Muggleborn, and that we would probably not be able to be close at school. And he explained about the Dark Lord and how he had to pretend to hate Muggleborns and Gryffindors – although I think he didn't have to pretend that last bit very hard – because when the Dark Lord returned, he would probably have to go back and pretend to serve him again. That's when he started teaching us Occlumency as well."

"At eleven?"

"We were six, I think," Draco said thoughtfully. "Although Hermione didn't develop the Library until after first year – she saw Beauty and the Beast when we were on hols and thought it was the most amazing thing she'd ever seen."

Harry pushed away from the table and ran his hand through his hair, making it stand up even more than usual.

"Right. Well. That's…"

"A hell of a story," Ginny finished for him. "It does make sense, though, in a weird kind of way. I always used to see you and Hermione coming and going from Snape's office in my first year. I'm guessing he was arranging for you guys to spend some time together?"

Malfoy nodded.

There was a long silence, and then Kreacher appeared with James Sirius dangling from one clawed hand, cackling like a loon – little James adored Kreacher – and his nappy bag from the other.

"Should Kreacher take the young Master to the Weasley house, Mistress?" the old house-elf asked. Ginny nodded quickly, reluctant to leave Harry and Draco alone for any length of time, and the elf was gone.

"Right," Harry said, clapping his hands together. "Let's get planning. Malfoy, we're going to need to know exactly where you found the entrance to that level. And then," his expression turned grim, "we have to decide who's going to fetch Snape."