(Post DH epilogue. Somewhat AU, but the major details of the books are still there. What's changed? You'll find out...)
The Hogwarts Express pulled away, carrying James and Albus Potter, Rose Weasley, and Scorpius Malfoy.
Hermione kept Hugo's hand in hers as they walked away from the platform, trying to hide how her heart ached for Rose. Her Rose. It had always been that way, ever since the unpleasantness when the St Mungo's Birth Facilitator had roused Hermione from her pain-free state and ushered Ron in to present them with a fair-haired daughter rather than the red-haired son he had been expecting. The flash of disappointment in his eyes had been brief, but noticeable, and in her hormone-addled state, she'd taken offense, and Rose's introduction to the world was marred by a blazing row between her exhausted parents.
Rose was her pride and joy, the light she'd clung to. The baby-blonde hair had soon darkened to a brown slightly lighter than Hermione's, thankfully without the bushy frizz, and her eyes were Ron's blue, but her soul was that of a bookworm. She loved learning, and reciting the interesting things she'd found to her doting mother, and she had absolutely no interest in Quidditch no matter how many fanbooks her father had tried to press on her. Without the burden of a ridiculous name or oversized hair and teeth, she ought to have had an easier time fitting in with other children than her mother had, but somehow she'd turned out shy and quiet, always waiting for someone to notice her and pay attention before she'd dare speak. Gryffindor? Perhaps - look at Neville, after all - but Hermione wasn't expecting it.
And now her Rose was gone, and the house would feel so empty. Hermione half-smiled to herself - clearly, she needed more hobbies.
There was Hugo, of course. For two more years, there would be Hugo. And bless his heart, it wasn't his fault.
It certainly wasn't his fault that Lily Potter had been born at the same time, and that the red-haired baby girl had been triumphantly paraded around by the glowing father. Hermione had tried to explain to Ron about Muggle genetics and recessive traits and how no one in her immediate family had red hair so she might /never/ be able to have a red-haired child, whereas in Harry's case it was surprising that it had taken them to the third... But all Ron saw was that his niece blended in with the Weasley clan, and his own offspring did not.
Hugo was a round-faced boy with muddy brown hair and brown eyes, who absolutely worshipped his father - which sometimes broke Hermione's heart, considering how that father had tried to disown him. Ron had had a little too much firewhiskey that night, and said things he would otherwise never have voiced... Accused her of cheating on him. Insisted that Hugo was fathered by this unknown lover. Wondered why she hadn't just gotten a divorce if she found him so lacking.
They'd made up again, of course, but it was never the same. The romance had been repeatedly stabbed and left, at last, to die. By now they were friends - good friends, but just friends - staying together for the sake of the children. When Hugo was of age to go to Hogwarts, they planned to separate. There was no rush, since neither of them was seeing anyone else, but there was no point in staying bound to each other forever either.
Hermione Weasley, her husband, and her son climbed into the battered-but-reliable Muggle automobile and drove away. To all appearances, a perfectly normal, happy family.
Dear Mum,
Ravenclaw!! But maybe Dad won't mind because this way there's a tiny chance I could end up Seeker one day? If I have to play, that's what I want to be. And I'd never get picked over the Potters. Except Albus turned out a Hufflepuff! Don't tell anybody! He's scared his dad will be mad but he's really happy there.
Oh, and Scorpius Malfoy is in my House! EWWW! Don't worry, I won't let him touch me.
But that's not the weirdest thing. The weirdest thing is the Scamander twins. Have you ever met them? They look just like those pictures of Dad when he was in school, both of them! And they got Gryffindor which I guess isn't so weird. I thought maybe they were cousins that got forgotten about or something but they said they're not related to me at all, except that you knew their mother, Luna? They're very funny.
Anyway I have to study! I just thought you'd want to know.
Love and kisses,
Rose
Hermione put the letter down, a queasy feeling in her stomach. In the kitchen, Ron was chasing a kettle around in circles. He was the same adorable bumbler she'd fallen in and out of love with for so many years. How could she doubt him now? And yet... and yet.
"Honey?" she called.
"Just a second!" Several clatter-and-bangs later, Ron arrived with tea and biscuits. "Well? How did she do?"
"Ravenclaw."
Ron only shrugged. "Well, she does have your brains. Got to feel sorry for the Gryffindor boys, though, without our Rose to keep them out of trouble."
"Mmm. Especially..." she trailed off. "Have you heard from Luna Lovegood lately?"
"Luna? Not since she married Rolf Scamander, I think." Ron dunked his biscuit in his tea and pulled it back out rapidly, just enough to melt the chocolate and not enough to make it soggy.
"Her sons are in Gryffindor. Twins. Red-haired."
Ron blinked at her, obviously waiting for her to get to the point.
"Rose says they look a lot like you," Hermione finished guiltily.
The cup clinked harshly against the table as he set it down. "You're not seriously suggesting..."
"Well, we have had our problems... and it's okay if you did, I just want to know the truth..."
"Hermione, look at me." His voice was surprisingly calm. "I never cheated on you. If I had, I'd've told you." He grinned. "If I'd done it to get back at you for something, I would have made sure you found out." Ron shrugged. "Besides, why me? If it was twins, it could have been George."
"George and Luna? He barely knew her."
"Not at school, but it's been a long time... who knows?" Ron stretched his legs in his chair.
"Of course, you're right," Hermione agreed. "People don't stay like they were at school forever."
Dear Mum,
I wish I had a friend like your Luna was, she sounds really fun. I like living with the Ravenclaws because everybody is polite and we help each other study. Right now my best friend is Harriet and she is a Slytherin but she's a Muggleborn like you. She is sneaky but nice and she likes to explore. We are finding lots of secret passages!
Albus and I have most of our classes together so we see each other a lot. Unfortunately we also have Scorpius in those classes and he's so mean! He's always picking on us and he always raises his hand first to give the answers so the teachers think he's so great and let him get away with things. He makes fun of us because we like to sit together and says that we're KISSING but I said that's not true because we're cousins and then he said something I didn't understand but it was really rude... I hate him!
Miss you,
Rose
Hermione stared at the wizarding photograph that had been enclosed with the letter. In it, Albus Potter waved shyly from his seat next to little Rose, who was grinning and holding the hand of a blond girl in Slytherin robes. Clearly, this was Harriet the Muggleborn. And equally clearly, it wasn't. The pale-blond hair, the refined features... if Draco Malfoy had had a sister, she would have looked rather like Harriet.
Something strange was going on.
Luna's sons were visibly Weasleys, but if she accepted Ron's word (and what reason did he have to lie?) then how could it be possible? George, Percy, and Bill all seemed extremely unlikely. She could have run into Charlie while out hunting rare magical beasts with her husband, but on the one hand that would have been awfully tactless of Charlie and on the other, family gossip had it that Charlie wasn't all that interested in girls.
Scorpius Malfoy looked as much like his father as James Potter looked like Harry - which was to say, not very, unless you squinted and tried very hard. Neither Hugo nor Rose looked like either of their parents. But Hermione knew she'd been pregnant and knew she hadn't slept with anyone but Ron.
Maybe wizarding genetics is different from Muggle, she thought glumly. All the purebloods are related to each other anyway, so it gets all mixed up?
It was a mystery. Hermione used to love mysteries.
It would have been easier if she were still at school. Back then, any question could be answered by sneaking into the Restricted section of the library. But now, she was just an ordinary adult, with a family and a Ministry job in the Department for the Regulation and Control of Magical Creatures. It was an important job, of course, but it didn't give her access to quite as many resources. It had been a while since she'd done any serious magical research. At work she was busy, and at home she had the kids and couldn't risk keeping books of forbidden magic floating around. Even a private potions lab was out of the question. Hugo had a talent for getting into things... luckily, nothing that couldn't be Reparo-d, so far.
Restocking her personal collection was high on her list of things to do post-separation.
Well, she'd just have to start asking around. Surely someone in Diagon Alley could point her in the right direction.
"Harry, why does everyone clam up the instant I start asking about bloodlines?"
Harry Potter raised an eyebrow across the table at Hermione. They were having lunch together at a little Muggle restaurant which did most of its business in the evening - it was practically empty. Also, not the sort of place anyone would look for one of the Ministry's most respected Aurors if they felt a pressing urge to interrupt his lunch break. "What do you mean, bloodlines?"
"Genealogy, records and spells to show who's related to whom... I know how Muggles do it, but not Wizards, and whenever I try to ask people get this funny look on their faces and say they don't do that sort of thing there and shoo me out," Hermione huffed. "It's like I'm asking for drugs or something."
"You are," Harry noted as he took a sip of his drink. "It's illegal."
Hermione blinked. "What?"
"They think you're a Pureblood researching potential marriage candidates for your children," Harry explained. "After the war, some laws were passed to try and fight the way the Purebloods considered themselves superior to everyone. One of them was to make it much harder for people to access any information related to family history, so that you can't find out if your girlfriend's great-great-great grandfather was a muggle."
"But... the families themselves would still know," Hermione pointed out.
Harry nodded. "Most of them have their own records, like the Black family tree at Grimmauld Place. It's not a very useful law. What were you looking for, anyway?"
"Oh... nothing," Hermione faked a giggle as she pushed her food around her plate. "You know me, always poking my nose into things."
"Something to do with work, maybe?" Harry pressed. "Trying to find out who might have a werewolf in their family tree?"
Now why didn't I think of that? Hermione mused. Harry's gotten a lot better at coming up with ideas. I must be out of practice. "If I were, I couldn't tell you," she answered at last, which seemed to satisfy him.
"That sort of thing might be kept out of the records anyway," Harry said, and took another sip of his drink. "I don't think there are any spells that would help. You might be able to get somewhere by analysing blood samples. I'm sure Teddy would donate to the cause."
"Maybe." Hermione quickly dug into her food, keeping her mouth too full to answer any more questions for the moment.
Blood magic. There had to be an answer there. Muggle paternity tests could tell whether two people were related from the blood, surely Wizarding ones could do better than that. But information would be hard to come by, with laws like the ones Harry mentioned in place to restrict pureblood privilege. What she needed was an expert in forbidden magic, blood and potions. Someone who wouldn't be averse to working around the law. Someone who didn't have children and thus wouldn't be offended at the very idea.
Someone like Severus Snape. If only he weren't dead.
But then, maybe that didn't have to be a problem...
(AN: Feel free to steal this and use it as a springboard for your own story. I may or may not continue past this point. Partly, I wanted to write a setup that stuck to canon and still allowed Hermione/Snape. It can be done! Partly, I felt like the Marriage Law scenario has gone on for far too long, and that we need some new ideas for Ministry stupidity.)