Title: The Descent of Magic

Disclaimer: J. K. Rowling and associates own these characters. I am writing this story for fun and not profit.

Warnings: Issues of disability, angst, epilogue-compliant.

Rating: PG-13

Pairings: Harry/Draco, past Harry/Ginny and Draco/Astoria

Summary: Harry Potter, retired Auror, is also a budding magical theorist who likes a quiet life. When he discovers what seems to be a possible reason that so many pure-blood families are losing their magic and having Squib children, he keeps it quiet, because he knows it would only cause a storm of controversy. But an equally budding acquaintance with Draco Malfoy might change his mind.

Author's Notes: The title of the fic and a few details of Harry's life are taken from the story of Darwin, who was also reluctant to publicize the details of his evolutionary theory, knowing the controversy that would result. Both Harry and Draco are older in this story and have had their epilogue marriages, so avoid if that's not something you like. Chapter lengths will be variable, and this will probably be somewhere around 18 or 20 chapters.

The Descent of Magic

Chapter Oneā€”Dust and Laughter

Harry blew dust off the books and shook his head. Kreacher had taken care of everything else in Grimmauld Place for so long. Why in the world had he missed this particular library?

Then he remembered exactly where he'd found the books-shut up behind a false panel in the attic, apparently for not being Dark enough-and grinned. Hard for Kreacher to dust them if he doesn't know about them.

Harry picked up an armful, weighed them for a moment, and decided they were light enough that his knee wouldn't automatically give out beneath him if he crossed the floor holding them. He limped back to his working chair and spread the books out on the table, studying them in the shaft of sunlight that fell through the window. Kreacher kept trying to light the fire in the small drawing room, and Harry kept putting it out. On a summer day like this, it wasn't necessary. He could wrap his knee in Warming Charms if he had to.

The book on the top was called The Descent of the Pure-Blood Lines, the one beneath that Living with Centaurs, and so on down the line. Harry shook his head again as he opened the first one and discovered a small date written inside the front cover: 1862. He didn't know how useful this particular one would be, given his new theoretical project.

Of course, all you have to do is tell Hermione you're interested in theory, and she'll be here in an instant with all the modern books you want.

Harry sighed. He'd leaned on Hermione too much over the years. He wanted to do something, find something new, for himself. Of course, God knew that he would probably stumble along for a while making "discoveries" that had been known for decades and crying out excitedly at things proven wrong. But it was still good practice for him to try.

He flipped a few pages further on and began to read.

"Master must eat!"

Harry emerged, blinking, from the book. He'd never known sentences seven hundred words long with sixty verbs, the way that most of the older authors seemed to write, could be so interesting. He looked down at Kreacher, who stood glaring up at him and tapping his foot, and then glanced back at the book.

"I need to?" he asked. His voice had a hollow echo, like someone talking from the midst of long, vaulted corridors.

"Master needs to," Kreacher said, and thrust the sort of plate at him that Harry might have managed to devour when he was a sixteen-year-old schoolboy at Hogwarts. Now, at forty-five, Harry poked uncertainly at a sandwich that looked as though it had been made by emptying fat onto the bread and picked up a fork to cut a tomato.

"Master must eat!" Kreacher pulled hard at his ears, a motion that Harry knew was out of exasperation, since he'd forbidden Kreacher to punish himself. "Master wishes to starve to death," he announced to the air. "Starve to death and leave Kreacher all alone." He bent down and glared at Harry's robes, as though he could see Harry's ribs through them. Harry rolled his eyes. Since retiring from the Aurors, he'd actually developed a slight paunch.

"I don't want to starve to death," Harry said. "Even if I did, I'd smell something of yours cooking and it would make me change my mind."

The joke fell flat, as most of the jokes he tried on Kreacher did. Kreacher gave him another unnecessarily dramatic glare, threw his hands up, and announced to the world around him, "Master is pleased to jest. Master is jesting. Faithful Kreacher is cooking, and Master is jesting."

Harry sighed. "Please go away, Kreacher. Go-" He had an inspiration. "Go make something chocolate." He did still like eating sweet things no matter how occupied he was, which was part of the reason for his slight paunch, and Kreacher took forever with the desserts partially because of that.

Kreacher beamed at once and hugged Harry's foot. "Master is not wishing to starve to death!" he shouted.

"Yes, yes," Harry said, and kicked a little to dislodge him. "Go away now."

Kreacher vanished, still smiling in ecstasy-which was a disturbing thing to contemplate on any house-elf's face-and Harry started eating the tomato, carefully holding it out of the way so it wouldn't drip on the book. Eating and reading together worked better than he'd expected, and by the time that Kreacher came back with a chocolate mousse held carefully aloft, Harry had learned more than he'd thought he'd absorb in such a short time.

Not that most of it wasn't nonsense, really, as any book about pure-bloods being really different from Muggleborns was bound to be. But Harry's biggest problem since his retirement was entertaining himself, and this was interesting.

"Harry?" The low voice came from his right side, and Harry rolled towards it, snorting an automatic question.


That was when he remembered that he wasn't married to Ginny anymore and couldn't conduct conversations in sleepy grunts with her. Harry blinked and sat up, making sure that his covers were pulled up to his waist. Sleeping half-naked didn't bother him, but he still felt a little self-conscious in his pants in front of his ex-wife, for many of the same reasons that he would feel awkward about doing it in front of Hermione.

Ginny lifted an eyebrow. "It's nothing I haven't seen before, you know," she pointed out.

"I know." Harry yawned, and didn't bother to shield the yawn. Ginny rolled her eyes. She was much more polite than he was, which Harry attributed to having a mum who cared and Ginny attributed to being female.

"Fine," Ginny said. "Al wants to know if he can visit you this weekend."

Harry blinked. He would have expected an eighteen-year-old to please himself. "Of course. Why is he asking permission?"

"Because he wants to bring Scorpius Malfoy with him." Ginny's voice was dryer than some of the old tapestries upstairs.

The tapestries that Scorpius had competently set on fire the last time he was here, Harry remembered. Never mind the banister he had splintered trying to slide down it, the first-floor window he had broken jumping out of it, and the bedclothes torn into strips to make bonds for when he and Al played Wicked Death Eater. Scorpius seemed to have decided that, as the first Malfoy ever to be Sorted into Gryffindor, he might as well go out and do idiotic, daredevil things with as much enthusiasm as his father had schemed and plotted.

That's a bit unfair, Harry reminded himself, and focused on Ginny again. "Yes, that's all right. But I'll be casting Preservation Charms on everything in the house before they come, so could they tell me the hour? And stick to it?" he added, remembering the one memorable time that Al had asked if Scorpius could come for "Christmas holidays" and then both of them had ended up at Harry's house three days before the term ended, with all of Hogwarts in an uproar searching for them.

"Done," said Ginny, with a bit of grim relish. "I'll get Mum to talk to them."

Harry grinned. Molly Weasley could be an unholy terror when she wished to be-

Including the day when she had found out that Harry and Ginny were divorcing.

Harry winced, remembering that time, and he saw Ginny's grin vanish as she remembered, too, or at least saw that she'd reminded him of it. She gave him an awkward smile a few seconds later. If they'd been in the same room, he thought she would have reached out and patted his hand. They made much better friends after their divorce than Harry would ever have thought they could.

"Yes, she'll talk to them," Ginny said. "And I'll make sure that Al understands you're too old to go chasing them around the gardens or demonstrate dueling techniques the way they'd probably like you to."

"I'm not," Harry protested, but Ginny had already vanished in a puff of green fire. Harry rolled his eyes and leaned back with a little grunt. She always had to get in the last word.

He glanced at the clock that sat beside his bed, made as a replica of the Weasley watch-which had died during the heroic duty of shielding his heart from a curse that might have stopped it-and cheered up when he realized it was only Thursday. He had another day or so before Al and Scorpius invaded (always assuming their definition of "weekend" was firmer than their definition of "Christmas holiday.") He could get up and do some reading in the meantime.

"Hi, Dad!"

Harry smiled and looked up at Al as he came through the front door, dragging behind him the two trunks that every young Slytherin seemed required by law to travel with. Behind him came Scorpius, smiling as he shook the rain out of his long blond hair. Harry's lips twitched when he realized that it was in a braid woven with bright streaks of red, although he wasn't sure if the red came from a spell, dye, or just ribbons. If Scorpius's father had seen that, he was probably still trying to recover.

"Hello, Al," he said, and turned his chair towards his son instead of trying to stand. The knee was misbehaving today; even light walking made him feel as if the joint had turned to water. Al gave him an exuberant hug, but didn't knock him down with his back-pounding the way he would have tried if Harry was standing. Harry smiled into his neck. So his children could learn.

At least, they can after an immediate scolding by their grandmother.

"Mr. Potter," Scorpius said, undoing one of the ties that bound his braid and revealing that the red did come from dye. Harry's lips twitched again. "Hi! How are you?"

"Not looking forward to more broken windows and torn carpets," Harry said.

Scorpius lifted his head with immense dignity that Harry actually could see him learning from his father. "I wasn't the one who tore up the carpet last time," he said. "That was Jamie."

Harry opened his mouth to remind the young berk that his elder son hadn't been with them the last time they visited Grimmauld Place-James was in Romania with his uncle Charlie, and had been since early last year-but then rolled his eyes as he remembered. Scorpius had named his large, mutant, incredibly dumb and friendly Crup after "the best role model a dog could have," a tribute that James had not at all appreciated. Scorpius claimed that the Crup had been crossed over with a poodle and was therefore supposed to be smart. From what Harry could see, the poodle had given Jamie shaggy curls that were forever straggling into his eyes and nothing else in the way of features, unless inverted intelligence was a feature.

Scorpius also claimed that Jamie was lying low so that he could astonish everyone with his intelligence someday. Harry thought it would have to be a bloody astonishing show after this long.

"You didn't bring him with you, did you?" Harry added, looking beyond Scorpius. There was no mutant Crup in sight, but that meant less than nothing with some of the pranks that Scorpius and Al had pulled in the past.

"I convinced him that it was for the best to leave Jamie at home, Dad," Al said smoothly, before Scorpius could say something that would hint darkly at the dog being in one of their boxes or waiting outside the house. "I think it's punishment enough for Mr. Malfoy to have to deal with him." Al smirked and threw his head back so that his own long hair spiraled over his shoulder. "He deserves it."

"Oh? What did your father do now?" Harry looked with some interest at Scorpius, who was rolling his eyes at the back of Al's head and looked a bit abashed at being caught out.

"Uh." Scorpius scratched the back of his neck. "He-accidentally sacked one of the house-elves," he admitted at last, as if that was something shameful. Or else his father had told him about Harry's history with the Malfoy house-elves and Scorpius had developed an unusual sense of delicacy in the last year, Harry thought. "He's been sulking about it for the past month."

"No different than Hogwarts, then," Harry said before he could stop himself. He felt his face flush a moment later. Ginny would scold him in a low voice and ask when he would grow up.

But Scorpius gave him a glance that flashed like lightning and flung himself down on the couch across from Harry. "Tell me more stories about what my dad was like during Hogwarts, Mr. Potter," he said, half-command and half-plea. "They're some of the funniest things I've ever heard."

"Scorp," Al said, in the tone of someone who had been afflicted with his father's Hogwarts stories more than he liked, although in reality, Harry hardly ever told them. He tugged on his friend's arm. "We have to go figure out how Uncle George made that Everlasting Song prank work, or he's going to get ahead of us."

Harry hid a smile. Al and Scorpius had developed the ambition to open their own joke shop to compete with Weasley's Wizard Wheezes. Al didn't seem to care that most of the people in the family would look on the ambition as disloyal. He'd started it, and what he started, he carried through.

Scorpius sighed noisily, rolled his eyes at Harry in a way that Harry was used to seeing from Ginny where Lily was concerned, and then stood up and said, "Coming, Al." He turned back on the way out of the room and mouthed to Harry, Later, okay?

Harry nodded back, amused. As far as he knew, Scorpius, a cheerful, bouncy, generous kid, carried out his rebellion against his father by being as Gryffindor as possible. But Harry could hardly blame him, not when Al had described the Howler Scorpius had received the day after their Sorting for being put into Gryffindor. Scorpius had crushed the ashes of the letter in his hand, his face pale. Then, the way Al told the story, Scorpius's face lit up. He'd come up with an immensely pleasing plan: if his father despised him for who he was, he would be that person to the absolute limits. Five minutes later, Scorpius had started a food fight that left Neville wearing cereal about his ears and had established his reputation as a troublemaker. Draco got far more letters about his son than he ever bothered to send.

He deserves it, right bigot that he is.

Harry turned back to the reading that Al and Scorpius had interrupted when they came into the room. It was a list of pure-blood families from the last several centuries, tracking the intermarriages and the numbers of children they had, including Squib children. Its author had been hounded out of the wizarding world when he published it, but Harry was finding it an invaluable resource so far.

And it had confirmed that some of his first impressions, and the public's first impressions, were wrong. Not all the pure-blood families were having fewer numbers of children, or fewer numbers of magical children. The Weasleys reproduced all over the place, of course, and so did the Prewetts, and so did the Bones family. They were the exception rather than the rule, but they were there. If there was some kind of magical infertility plague afflicting the pure-bloods, the way that people like Rita Skeeter kept insisting, then it had mysteriously missed out on some of the most fertile victims. And it couldn't be due to the admixture of Muggleborn blood, either, as Malfoy kept arguing in some of his published articles, since those families were among the ones most welcoming to Muggleborns.

Harry shook his head. It was a mystery, and he hardly expected to find the answer all by himself. But it was something to dig into, and he knew well enough that his greatest danger in living alone was boredom. He dipped back into the book.