Ugh. Ed had forgotten what a pain in the ass manual prosthetics were.

"Thanks for getting this for me," Ed said, gingerly testing his weight on it. He rocked on his heels a little, and then took off at a confident walk. The prosthetic held, obviously, and it seemed like his control hadn't gotten too bad over the years. "Hey, how much do you know about this thing's specifications?"

"I don't have any prosthesis training myself, but I know the spells to check the enchantments on it, if you need," Madame Pomfrey said mildly. "Ask your questions."

"Can I run on it?" Ed asked, eying the floor ahead thoughtfully.

"Certainly," Pomfrey assured him without even checking, so it was clear that she knew at least a little on her own. "Along with the cushioning charm on the socket, there should be spells at the knee and ankle to provide you with ample suspension."

Ed grinned. "Nice." Without further preamble, he lunged forward and dashed about halfway down the hall. Skidding to a halt made him stumble, though, wobbling violently as he tried to keep his balance. Plenty of suspension, but it sure didn't have the motor control for athletics. A damn good knee though. "Ugh. Huh, can you spell it so it doesn't slip off my thigh?"

"Is that a problem with Muggle prosthetics?" Pomfrey asked with some bemusement.

"Only if you try to kick people with them," Ed said, and Pomfrey muttered something under her breath, then looked at Flitwick. Flitwick nodded eagerly.

"Yes, yes, certainly!" he assured Ed, scurrying over to tap the socket with his wand. It glowed briefly, and he stepped back and gave Ed a nod, eyes sparkling.

"You're very excited about this," Ed pointed out. Flitwick chuckled.

"Ah, do pardon me, it's so very rare for me to be able to exercise my creativity these days. To receive requests that are not only of a nature I've never considered before, but also asked by someone completely inexperienced with the use of magic – why, I assure you, Professor Elric, I'm having quite a good time."

"Flitwick is the head of Ravenclaw House, which prides itself on its wit and intelligence," Pomfrey informed Ed. That did explain a lot.

He took a couple steps back, and then struck out with his new prosthetic. The socket stayed firmly in place, and he smirked to himself, shifted, and swung onto the prosthetic so he could kick with his flesh leg. He nearly fell over. "Augh!"

"Are you naturally given to clumsiness, Professor Elric?" Flitwick asked. Ed shot him a filthy look.

"Only when I'm controlling a whole leg with just my thigh," he said tersely.

"I don't mean anything by it, I assure you," Flitwick said, bouncing on his toes. "It's only that I believe that a simple balance spell might be of help. It should keep your leg from wobbling quite so badly."

Ed frowned. "Huh. You can take it back off if it makes things harder, right?"

"Of course, of course!"

"Alright," Ed conceded. "Give it a go."

This spell seemed a little more complicated, in that Flitwick flicked his wand artfully through the air, brow furrowed in concentration and murmuring under his breath. Ed waited for something to happen, but nothing did.

"Try it now," Flitwick said at last, eyes bright.

Warily, Ed stepped back and tried the kick again. No wobbling this time; the leg held relatively still under him, and still turned when he needed it to help absorb the force of his landing. He jogged down the hall, stopped a few yards away to consider, and then jogged back.

"It's not bad," he said, most of his mind still on the movement of his body. "It's a little too still though. Can you loosen it up around the ankle or something? It's kind of dragging."

Flitwick waved his wand and murmured, and then nodded. Ed jogged to the window, and when he came back, he was grinning.

"That's great," he said honestly. "Thanks."

"As good as your 'automail'?" Pomfrey asked, with what appeared to be sincere curiosity. Ed snorted.

"Nowhere near. Trust me, you don't fucking appreciate how goddamn complicated legs and feet are until you lose one." He swatted his thigh. "This'll last me the year, but I'm gonna miss having biofeedback." He considered. "It's not as heavy though. My muscles are gonna atrophy, and my goddamn shoulder. Is there a spell for that too?"

"I'll have Severus brew the necessary potion," Pomfrey assured him. "It'll need to be taken about once a week, but it's meant for coma patients, so it should be more than adequate for this."

Absolutely fucking incredible. Despite the unforeseen complications, Ed really, really wasn't regretting his decision to come here. Magic was so goddamn cool.

"On the topic of your shoulder," Flitwick said, "I wondered if you would be willing to share why you didn't ask for an arm as well?"

Ed scowled. "I haven't decided yet if it'd be worth it. I guess I can go out to that hospital – St. Mungo's? – and ask, but like, arms are ten times worse than legs, easy, and twice as bad again when you don't even have a stump. I'd have to get it fitted, I'd have to learn how to use it, fuck, I'd have to pay for it and by then it could damn well be halfway through the school year." He shrugged. "It's just a year, and then I'll have my automail back on. I'll probably just do without."

"A very thorough and complex answer, thank you," Flitwick complimented, seemingly on automatic, but he looked pensive. "I hadn't realized that there was much difference. I suppose even magic has limits."

Yeah. No kidding.

"Can you do something to keep shitty kids from messing with it?" Ed asked, wanting to get away from the topic of his arm. Yeah, that one stung.

"Already done!" Flitwick assured him, smiling ruefully. "It will repel any jinx cast on it, and anyone who attempts to touch it without your explicit consent will find their fingers swiftly locked together."

"Love that," Ed admitted, cheered by the thought. "Alright, that just leaves the wheelchair. Dumbledore said you could make it take stairs like ramps?"

"Ah, you're still using that?" Flitwick asked with some surprise, but he also turned toward the chair and started casting spells, so Ed forgave him.

"Yeah," he said. "It's good to have a backup in case the leg breaks, and sometimes extended use can make a guy real fucking sore. If I'm gonna be stuck with a manual leg, I want to have a wheelchair around just in case. Oh, can you cast the spells to keep people from touching it again? People always want to fucking touch wheelchairs."

"Done," Flitwick promised him, without pausing in his spellcasting. "A leg-locker curse ought to be appropriate punishment for that, don't you think?"

"I do like the sound of that," Ed agreed, amused. "Hm... can you like, make it so I can propel it with my good leg easier? It's a shame to waste it. Maybe synchronize the casters too, make it easier to steer."

Flitwick clicked his tongue thoughtfully. "The casters?" he asked. Ed indicated the two little wheels in front. "Ah, that should be easy enough. As for your other request..." He pondered for a while, and then suggested, "Perhaps a lever you can press with your foot to move forward and back?"

"Perfect," Ed said, and Flitwick got to work again. Ed leaned against the wall and watched. "Thanks for this. I know you didn't exactly ask for a lesson on prostheses."

"It's quite welcome," Flitwick assured him, still flicking and twirling his wand. "Any day I learn something new is a good day."

Ed smiled. "I get that," he admitted. "The arm thing is gonna be an issue though. Longest I've gone without one was about two months, and I didn't have to do anything then."

"Perhaps you could request one of the house elves to act as an assistant?" Flitwick suggested. Ed grunted in confusion. "Ah, of course, you wouldn't be familiar with them. Hogwarts employs just over a hundred house elves to take care of the day-to-day care of the castle – cleaning, laundry, cooking, that sort of work."

"Makes sense," Ed said thoughtfully. "Must get expensive though, that big a staff."

Flitwick chuckled. "House elves aren't paid in coin, Professor Elric – the idea quite disgusts them. They're given room and board, and as they're quite communal by nature, the same is of course plied to their children, their sick, and their elderly. There's around fifty house elves dwelling in Hogwarts that are not technically employed by the board."

Alright, that was better than Ed's first impression had been, but he was still pretty uncomfortable. "This is extra work though. You sure I can't pay them for that?"

Looking indulgent, Flitwick opened his mouth, paused, and then said, "Dobby!"

A crack like a breaking branch echoed through the hall, and Ed jumped. A little wrinkled elf – those ears were pretty unmistakable – appeared in front of Flitwick, looking expectant and bouncing on its heels. They were about the same height. Dobby was wearing an assortment of random clothes, like he'd picked them out of a dumpster, including a tea-cozy hat all pinned up with badges.

"Dobby is a new addition to Hogwarts' staff," Flitwick explained to Ed, making Dobby look over at him, eyes bright and curious. Ed had to smile. "He's rather peculiar for a house elf, and I believe he'd be quite delighted to be paid for a few additional tasks, wouldn't you, Dobby?"

Dobby lit up. It was kinda cute, despite how weird-looking he was. "Dobby certainly would, sir! Dobby only wants to know what it is he would be doing."

"Hey," Ed said, discomfort and amusement playing oddly together in his stomach. "I'm Ed, I got called in to do Dumbledore a favor. But the magic here fucked up my prosthetics, so I'm down an arm." He gestured, drawing Dobby's attention to his cut-off shoulder. "So I'd need help with some basic shit – carrying things around and reaching for stuff, mostly. I could give you, what, a third of my pay?"

Dobby's eyes went round, and he shook his head violently. "No, no, that is far too much, sir! Dobby will take no more than a Galleon every other week!"

He looked pretty determined about that. Ed looked at Flitwick.

"He's currently being paid one Galleon a week," Flitwick explained. "He talked Albus down from ten."

Okay. Weird.

"Alright, a Galleon every other week," Ed agreed, figuring he wasn't about to understand house elves in a day. "What do I do if I need you? Just say your name?"

"Yes, sir!" Dobby exclaimed, bouncing in place. "Thank you very much, sir!"

Ed gave Dobby a small grin back. "Thanks to you too."

Dobby squealed.

At some point, Madame Pince brought out a cart for him to put his books on, which Ed thought was the best idea he'd heard all day.

The Hogwarts library was massive – easily as big as the First Branch back in Central, though it of course had nothing on the entire five-branch collection. Three floors, dozens of tables, hundreds of shelves. Ed was having the time of his damn life.

He let the Gate pick his books for him, pulling down the ones that seemed to almost ring a bell in his head. Most of them were arithmancy or magical runes, but opening any of those books made it apparent that he didn't have nearly the magical background he needed for them, so he'd started grabbing anything that caught his fancy.

"I suppose you'll be setting these aside for some time?" Madame Pince asked dryly, giving his cart of books a mournful look.

"Hell no," Ed dismissed, pulling down another and propping it on a shelf to flip through it. "No, I'll be done with these today, don't worry about it. I mean, I might take a couple back to my room if I think I'll need to refer to it often, but these are just what I think I need to get started."

"Ah, you're of Filius' ilk," Pince said, and Ed snorted without looking up, adding another book to the cart.

"Yeah, I guess," he said dismissively. "Hey, if you had to pick some primers for learning magical runes, what would you pull out?"

He ended up with a full cart of books, which he pushed toward a large study table not far from the main exit. Then he sat down and started reading.

It had been a long time since he read so much without understanding any of it. That didn't stop him, of course, just as it hadn't stopped him from learning alchemy; he let his mind chew through the theories and the terminology while he reached for the next book, and made a mental note to return to it later. Slowly, a picture began to form in his mind, a blueprint of the laws that magic operated under.

"It's almost like wizards are drawing a transmutation circle without realizing that's what they're doing," Ed muttered, flipping slowly through the book on the table. "Wand movements instead of base matrices, incantations in place of runes- it makes me wonder if arithmancy is just a way of notating and quantifying those components. It's not exactly the same, they don't look anything alike, but the similarities are too pronounced to ignore."

"Does this mean you are not wanting supper, Professor Elric, sir?"

Ed blinked, pulled out of his thoughts, and focused on Dobby, who was shuffling nearby, offering Ed a nervous smile. Ed blinked again, and it took him another moment or two to pull himself out of the mire of magical research.

"That late already?" he asked at last, baffled. "Maybe something quick, I'm gonna be working on this for a while."

"Of course, Mr. Professor!" Dobby agreed cheerfully, and cracked away. Ed smiled briefly, then turned back to the book, quickly losing himself in the basics of spellcraft again.

Crack. Ed didn't even look up until Dobby set the plate by his elbow.

"Ah, shit," he muttered. Dobby flinched.

"Is something unsatisfactory, Mr. Professor?" Dobby asked anxiously, already twisting one of his ears. Ed glanced at him and shook his head.

"Nah, I just realized I'm gonna have to actually take a break," he said ruefully, pushing the book away. "One hand, can't eat and turn the page at the same time. Thanks for the sandwich."

Dobby looked relieved. "Dobby can turn the page for you!"

Ed wasn't that desperate. "No thanks. I've been reading all day, it's probably good to take some time to actually think about it." He grabbed the sandwich and took a bite, mulling over the contents of the books, and before he realized it, he was talking again, rambling between bites. "I can kind of see where basic arithmancy is gonna turn into the circle I'm studying, but it's definitely some next level shit, so I've got a ways to go. Everything I've read so far has been about exchanging energy for energy, making things happen, but I really need to get into how magic works with materials, and then I need to get into how it works with the metaphysical. What a pain in the ass."

He paused to take a bite, frowning at nothing. He had a lot of work ahead of him, for sure.

"Mr. Professor must be very smart, if Headmaster Dumbledore is asking him for help with advanced magic," Dobby said haltingly, making Ed start and look at him, still chewing. Dobby cringed, shuffling his feet. "Mr. Professor was talking, so Dobby wasn't sure if he should go!"

Ed swallowed his food. "I talk to myself a lot when I'm figuring something out," he explained. "You don't have to stay if you don't want to." Dobby planted himself on the table, looking astonished at his own daring, and Ed smiled briefly. "I'm an expert in a very specific field of alchemy, but that's only about half of what I need to know for the favor Dumbledore's asking, so I gotta learn the other half from scratch. That's what I'm working on now."

Dobby looked at the piles of finished books. Ed winced.

"Uh, I'm gonna put most of those back," he assured Dobby sheepishly. "But I'm basically trying to reverse-engineer a circle that hybridizes alchemy and wizard magic, so I need to know..." He waved the sandwich at the books. "And all of the alchemy parts of it seem to deal with..." He cut himself off, rolled his shoulders uncomfortably, and amended, "The alchemy is pretty advanced. Seems logical to assume that the magic isn't just nuts-and-bolts."

"Mr. Professor didn't take any fancy books," Dobby said tentatively, and then cringed like he expected to be hit. Ed sat back and considered him for a moment.

"I'm not gonna hurt you," he said bluntly, and watched Dobby flinch again. He exhaled. "Ask as many questions as you want. Talking about it helps me think about what I'm learning. 'S useful."

Dobby brightened instantly. Ed suspected that the little elf's life was a little bit fucked up. "Dobby doesn't know very much about wizard magic!" he said earnestly. "Why does Mr. Professor need to know arithmancy if he knows the rest?"

"Cause they're doing different things," he explained, and pulled over his rough sketch of the circle to show Dobby. "I can tell what the alchemy parts of the circle are doing – the base matrix roots the whole thing in the metaphysical, and this central rune indicates that it's used to hold something, like a seal. And all of these are output runes, but all of their input runes are magical, so I can't tell what's going in, which makes it hard to tell what's coming out."

Something in the back of his mind clicked. Of course – he didn't need to completely learn arithmancy from scratch. He just needed to know enough to decode the meaning of the remaining pieces from context.

"Huh," Ed said. "I need to start writing stuff down."

He was still doing that, physically notating the purpose of all of the runes he already knew and attaching images of the magical runes related to them, when Dumbledore sat down nearby. Dobby squeaked and disappeared.

"It's like breaking a code," Ed muttered to Dumbledore, most of his focus still on his work. "I'll figure it out faster if I use context clues to help me learn what these things are doing."

Dumbledore picked up some of his notes and scanned them. "Fascinating," he murmured, but set them back down without being helpful or anything.

Ed finished copying down all of the connected runes and pushed the parchment away, and stretched with a grunt as he realized it had been at least a couple of hours. Finally, he looked up at Dumbledore and cocked his head. "What's up?"

Dumbledore smiled. "I thought we would discuss your class before the school year began," he said, with a touch of humor. "How would you feel about it being arranged as an extracurricular?"