He had the ability to relive that night.

It wouldn't be difficult for Harry to sit down in some calm quiet, and analyse moment by moment exactly what happened after he drank the potion.

It would be even easier to walk straight to his Pensieve – less than six steps from his desk! – and dive inside the silvery memory liquid to watch the whole night from a clearer perspective.

At some future point, he was probably going to have to.

But, as Harry Potter twitched his limbs just before six in the morning near the top of Hogwarts' Astronomy Tower, all he wanted to do was forget it.

A scream of pain from overstimulated nerves and tired muscles met him. Fingers spasmed on the end of his arms. They were human arms too, once more. So at least there was that going for him.

Things had gone arguably well the night prior: the discovering the Gryffindor couple in flagrante delicto was an embarrassing but amusing Hogwarts experience.

The twins pulling him aside for a conversation about the Dursleys could have been horrendous; Harry had mental images of medi-witches descending upon him in concern, social services wanting interviews, reporters publishing exposés …but of course, this was Fred and George, and they followed the beat of their own drums. They offered concern, wanting him to be safe. They offered help, in case there was anything he needed to escape or protect himself. And most of all, they trusted him, even when he said he had everything under control.

Harry wasn't used to people assuming he was competent, not in the big things in life, and it was rather nice to know they had his back.

But in the aftermath of one of the best and worst nights of his life, the rest was all draff.

Most urgently, the animagus potion had been brewed to perfection – even if it had passed its most effective moment by over a fortnight. The Welsh adaptation to the process had worked far better than Harry had allowed himself to hope, the spells being precise, the potion variables responding as they ought. Everything had worked together to bring the four phials of animagus brew back to peak readiness and efficacy.

He'd borne the worry of his new form: he'd narrowed it down to three, a snake the most worrisome. But even if Sirius didn't want him anymore, Harry would live it. It would be him, after all. Forked tongue and all.

He'd felt the terror rush through him, like how he imagined a sky-diver might felt just before they jumped. Or a player of Russian roulette just before they clicked the trigger. A mad leap of fate. Letting go of control – and these days Harry loved having control. But however the chips would fall, everything was about to escape his grasp now.

Then he'd drank the thing.

He'd expected the pain.

From the moment that Harry had first studied the animagus process, in his first go through third-year Transfiguration under Professor McGonagall as a purely theoretical exercise, Harry had understood it was a big deal.

It was obvious that a wizard changing his body into that of an animal's would hurt. He knew that as his body shifted and he used new muscles in different ways, things would ache and complain.

He knew that his bones and his tendons might feel stretched or squashed because of the size differences and movement where, previously, movement hadn't been.

And, different to normal transfiguration, he'd realised early on that the initial shift would obviously be more intense because this time, Harry was building the blueprint into his body. It would always be there, ready for access, after this.

He'd be all wizard and all animal. All the time. Physical form immaterial.

An animagus was always indelibly changed by the process.

But like a tattoo hurting while it was applied, and even while it healed, Harry had expected a similar process.

What he hadn't expected was how unnerving it would feeling to have two heartbeats converging. It was more than just two rhythms in his ribcage. It was more than how his blood-pressure rose and small veins burst in his eyes, or how pressure throbbed in his neck and his temple like needles.

It was the feeling of chasing and being chased, and the sudden awareness that his body was animalistic; it was an absence of justification and analysis and, for what had seemed like forever, merely overwhelming emotional responses undiluted by any human thought.

It was the sudden development of a whole new set of instincts: prey and predator; locational awareness – where north was, for some reason, amidst more; too-fast fast-twitch reflexes; some kind of sensory guide that wasn't sight, sound, scent, touch, taste.

…Others he couldn't name yet.

It was the weird sense of his soul shifting – Harry hadn't been sure he had one, before this, but now he knew. Now there was two of him.

First Harry; Second Harry.

Old Harry; New Harry.

Dimly, as he'd flailed around in Hogwarts bartizan overnight, all awkwardness and gracelessness as he learnt his new form, and then somehow returned to human shape after he'd collapsed in exhaustion, Harry began to realise why wizards seemed to give their animagus forms names.

As the first light of the pre-morning grey registered behind Harry's eyelids, he blinked them open with a groan that sounded more like a whimper, and learnt he was still Harry.

And, in the silent morning broken only by the distant and indistinct chirping of the dawn chorus, the air chilly and damp on his face and hair, Harry Potter registered a blazing glory of colours, like hundreds of multi-hued suns, blinding his eyes and drilling into his brain with white-hot fire. His eyeballs rolled up, his body spasmed and Harry threw up until he passed out for a second time.

Harry was woken again by the sound of voices arguing over his head in a rather familiar manner.

"—but it can't have been the potion, because we're fine! Even Lee's fine, and he's not nearly so good at the Transfiguration side."

"Oi…I think."

"Is it the age?"

"It's not a ruddy repeat of last year now, is it?"

"Can't be. There's no blood in the vomit this time."

"…Wait. This has happened before?"

"Oh, Lee. Forgot you were there for a minute, mate. Story for another time."

"…So…Harry like…this is a regular thing then?"

Harry tried to open his eyes, but everything hurt. Even the back of his eyeballs hurt. The blink aborted before it began and turned into a pained scowl. "…Ngh…"

"Oh, blimey. We didn't consider the Ti—er, Harry's secret now, did we?"

"Crap!" A horrified pause. "…But it shouldn't make a difference, should it? My instinct says no."

"You're the potions expert, you'd know better than me."

Lee's voice snuck through Harry's pounding heartbeat that echoed in his ears. "Uh…did you hear him just now?"

"Alright then, what does that leave?!"

"The only potions he's on are ours!"

"Oh bollocks, I thought we knew most of his secrets now. Do you think there are more?"

"He's not a dumb kid. He would have mentioned it if there was something that would have affected the process…right?"

"…nnmph…"

Lee spoke louder into the hurried argument. "Guys? Fred? George?"

Harry felt air brush his face as if someone was shrugging or flailing their arms quite close to his head. "Well, he might be a hot-shot but the kid isn't exactly the two of us, is he Forge? Would he even know? He is better with spellwork, after all…"

"Damn it. How much of the adaptive measures did we tell him about exactly?"

"…Surely he hasn't undergone any other rituals recently, has he?"

Bless Lee for persisting. "He's waking up, guys!"

Harry kept his eyes decisively shut.

The floor was uncomfortable, the stone was cold on his face, and the wind was still chilly on Harry's exposed face right up until the moment that Fred and George shoved their heads over Harry's, casting cold shadows on his face. They were so close he could feel their breath puff in and out on his neck.

Harry carefully stretched his muscles and let his fingers and toes twitch and stretch; yes, they all seemed to be there. Were definitely there, in fact, due to the screaming muscle and nerve pain.

Some kind of anguished groan was squished out of his lungs.

"Oh thank Merlin! You live yet another day, kiddo!"

"How is it? Lungs working alright? Got all your bones back? Brain human again?"

"What went wrong with the Transfiguration? Can you talk? What hurts?"

Nerves overly-sensitive, Harry wondered if he was imagining the twins with their wands out, tracing over his prone body, searching for spell damage. Harry groaned again and tried to straighten his neck even as his face pressed into the floor.

Even with his eyes closed, he could still sense the cacophony of colour waiting for the moment he let the light in.

"Ngh," Harry moaned again, vainly attempting to straighten his body. He was lying on one wrist, for some reason, and the smell of his own vomit from a few hours ago was unfortunately close to his face. "Everythin'."

The general impression of Fred and George's heads retreated for a bit and out of sight behind Harry's head. Harry didn't catch their whispers despite the calm of the morning air. Probably the pain.

After a bit, George spoke louder. "Can you open your eyes? What hurts specifically? At what time do you think you vomited?"

Harry frowned, eyes still shut tight against the encroaching chaos: he could feel the coloured lights threatening. At least his voice grew steadier. "Everything. Eyes, head, brain mos'. When I woke up the firs' time."

Fred spoke this time. "Can you open your eyes to let us take a look?"

"No." He couldn't have sounded more stern if he was instructing the Patronus Club. Even if Harry's voice was still soft and pale sounding, it was as hard as stone. "Tha's why I threw up and fain'ed las' time." He paused, gathering his scattered thoughts. Thanks to his occlumency he could fight the pain away somewhat and consider other things. "Help roll me over?"

After more mutters, someone's arm slipped carefully under his neck. Someone else grabbed his knees and when the third pair of hands grabbed his free arm, Harry was prepared to be carefully if awkwardly rolled over to lie on his back.

The sunlight was brighter now despite his closed eyes and, despite his lack of effort, the muscles all over Harry's body screamed with the movement. A few hands straightened him out, arranged arms to rest on his stomach, straightening out legs to lie flat, twitching his robes to rights again.

More spellwork seemed to be going on above him, blossoming in brighter colours than Harry felt he quite deserved, and Harry just lay there, slowly regaining feeling in his numb arm through the encroaching prickles of blood returning to his hand.

Eventually, the intensity of the sunlight he was trying to ignore reached an intensity where he realised that night time – and secrecy – was running out. "Wha's the time?"

While Fred and George cast more spells and muttered to each other, Lee shuffled up to sit by Harry's head and spoke quietly. "It's half past seven. Breakfast has been open for half an hour, and we've been waiting for you since a little after six."

"Huh." His mind moving like treacle, Harry thought for a while. "…When I woke up before, the birds were just beginning to sing up the sun."

Harry felt Lee nodded. "I'll let them know. Is there anything else you need, Potter?"

Harry snorted and felt the stabs in his forebrain again. "Harry. After all of this, at least."

He heard Lee's breath catch a little in his chest, hiding some kind of snort or chuckle. "Is this really the moment? But alright, alright. Harry it is. Anything else?"

A pale imitation of a grin flitted over Harry's lips. "A muscle relaxant or pain potion?"

"I'll see if it's safe for you. Gimme a moment."

The feeling of Lee's body moved away with some rustles and the scrape of shoes against stone. Harry straightened his body up a little more, finally twitching himself properly straight, and stretched the worst of the muscle knots out as he did so.

He took a moment to breath deeply and felt that the birds were singing louder than normal this morning. Obnoxious things. His head throbbed with pain, the worst of it stabbing sharply right behind his eyeballs.

After some furious muttering and the feeling of phantom lights blossoming behind Harry's eyelids, Lee shuffled back and knelt near Harry's head.

"We figure it's safe for you to drink. Your Transfiguration has gone fine, as far as Fred can tell. George hasn't found any problems with the potion and from what we can figure, this is some kind of weird side-effect; the animagus bit itself seems to have worked fine. The rest of us woke up absolutely fine except for some incredible body pain, which seems to be the easy half of what you're complaining about. I've got a potion for you."

Harry grunted.

"Er. Can you sit up?"

After a moment of struggle, Harry moved past flailing around like an eel and managed to get an elbow underneath him.

"Gimme some space, yeah?"

"Alright, alright."

He levered himself up like some kind of aged grandfather and a groan squeaked out while he did so.

"Oof," Harry mumbled as he forced himself into a proper sitting position. "My thighs."

Lee chuckled, in what Harry would later decide was probably an understanding kind of snigger but currently felt a little cruelly cheerful, and forced a cool phial into Harry's right hand.

"Here we go then, Harry. You got that?"

The tendency to open his eyes to see what he'd be given was strong, but he didn't get far before more brilliant lights snuck past his eyelids and stabbed straight into his brain again. Harry's eyes watered: the stabby pain made his stomach roil.

A bit embarrassed by all the weakness he was showing, Harry felt himself blush hot all the way up his neck and then forced his spine straight with the determination of years of discipline.

This wasn't even the cruciatus of a Dark Lord, for Merlin's sake. This was just muscle stiffness, and he'd done it to himself.

He clutched the thing in his hand tightly and brought it to his lips with slow care.

Pulled muscles right through his body screamed and groaned as Harry slowly adjusted his posture. The worst of the pain suddenly shot up his bicep, his shoulders, and down the big muscles in his back, but Harry had faced worse.

He might have grimaced a bit, but he couldn't read Lee's face to tell if it was noticeable; he barely twitched as his thigh muscles got in on the job and shrieked in protest.

He might have let out a pained grunt and tilted left a little; that was as far as Harry was willing to admit. He'd had worse, after all.

Over the mutter of George and Fred in the background, Lee's slow murmur reached his ears. "Careful, alright? Just…the top's open, okay Harry? So don't spill anything. Bring it slowly to your mouth…that's right. If you feel anything like we did when we woke, you'll want to take all of it, I reckon. How are your eyes?"

Harry swallowed in hurried gulps that had the toxic-tasting potion sinking to his stomach immediately.

"No more, I don't suppose?"

"Sorry, mate."

Blessedly, the pain began receding from Harry's body even as an odd surge of colour and light washed at Harry's closed eyes.

He grunted again, fought the light down through sheer stubbornness, and focused instead on the tingles in his fingers, the stretch of his legs.

He could feel Lee remain kneeling beside him as Harry's slowed, from the hurried, painful gasping to a steadier, calmer breath; his back muscles relaxed with the warmth of the sun and the rhythm of his breath; Harry felt his forehead uncrinkle as his body pain began to relax, even as the sparks in his eyes grew brighter.

"Eyes might have gotten a bit worse," Harry bit out.

Lee swore. "Well, I can try to distract you for a bit. Did I ever tell you about my family?"

"I don't think so?

"So I've got this little sister, right? Her name's Meredith; she's three and a quarter – which is very important to her – and she's a stubborn little thing," Lee's soothing voice began murmuring near to Harry's side. "Rather like you, actually, Harry. She's always escaping Mum's eye and getting herself into trouble. There was this one incident with the neighbour's dog, you see, that I'm never going to let her forget…"

By the time that Fred and George had finished their argument, Lee had finished his stories and Harry had digested the pain potion as well as he was ever going to.

He was feeling significantly better, his muscles didn't hurt at all now, and his stomach only twinged when he tried to open his eyes.

The blinding colours were still there, unfortunately, and every time Fred, George or Lee tried to get him to open his eyes, Harry would gag, groan and regret it.

At eight-fifteen in the morning, just before breakfast would end, the four Gryffindors found themselves sitting in a circle and deciding on what to do next. Harry had a Gryffindor scarf tied around his head to try and keep the lights out; mostly, it seemed to work.

"That's it, I'm afraid," George had announced to Harry and Lee apologetically. "I've run all the spells that I know. None of the potion side-effects I've ever read about explains this, and I don't know the counter to it."

Fred nodded next to George, and Harry could feel the movement from where he sat between them in the morning sun.

"None of the charms or transfigurations I know of can explain this either," Fred agreed. "I've cast as much as I can on you kid. I'm out of options."

Harry tried to look at the voices, but was only mildly sure he was pointing his face in the right direction. He'd never really been functionally blind before, after all. It turns out that he didn't like the experience.

Not that it mattered; all they would see was the scarf knot being pointed in different directions.

"I was seeing the lights before actually, just dimly," Harry offered. "So…maybe they'll fade away by themselves again?"

There were three groans.

"Dork," Fred spoke up. "You should have said something!"

Harry shrugged. If he'd thought about it, sure…

Lee spoke up. "So…what are our next steps then? Shall we take him to Madam Pomfrey or no?"

There was a pause. Fred spoke first. "Well, that's the question, innit? Is it safe to send him to the Infirmary, Georgie?"

"Is it safe to leave him untreated, Freddie? I mean… best case scenario this is just some kind of over-sensitisation, don't you think?"

"Ooh!" Harry spoke up. "I've had that before actually; the first time I figured out how to sneak out of the boys' dorms to Hogsmeade I mixed two spells badly. It's…actually quite similar to this, now I think about it."

"To Hogsmeade from the dorms?" a twin asked, before, "Wait. We can talk about that later, Harry. What do you guys think then?"

"Does Madam Pomfrey test for…unusual states if students go there, though?" Lee spoke up again. "I mean…we weren't planning on registering our forms, were we?"

"Well, no," Fred admitted, while George spoke up to say, "But Harry's health is obviously more important…"

Harry bit his lip. "I do need my form to be secret actually, for…reasons."

"Yes, but—"

"Big reasons, unfortunately."

"See!" Fred crowed. "I knew he still had secrets!"

"Not now, Freddie."

"Oh, fine …"

Harry sat with the older boys blindly and played experimentally with the movement of his fingers. Turned out that you noticed an awful lot more sensory stuff when suddenly you couldn't get your eyes to work properly. The scarf was warm and a little bit rough against his eyelids. The wind carried the faint scent of pine pollen and damp earth.

His left-hand and right-hand fingers pressed against each other, and they played an absent game of push and shove while Harry's mind followed the conversation.

"Speaking of which," he spoke up, "how did your transformations go?"

"Great."

"Good."

"Awesome," resounded in his ears, and Harry let slip a smile as the boys suddenly let the tension drop and reclaimed their pride and excitement for what was probably three minutes.

"I'm just the most gorgeous, I am," Fred claimed grandly. "They say you get faster and faster in the transformation from this point on, and I'm going to be absolutely stunning when I speed up the shapeshifting a bit – less time in a half-formed shape, you know."

"Have you even seen yourself yet?" Lee asked, while George argued, "Hang on a minute here, I'm the better looking of the two of us."

They squabbled. Harry grinned.

"And what's your form, Lee?" he raised his eyebrows in the general direction of Lee's voice, feeling them brush up against the tightly bound wool. "Pine martens aren't really a surprise for those two, we owled each other often enough over the break, but I've never spoken to you about it."

"Oh, turns out I'm a crup," Lee said casually. "Looks like there was enough British in me after all."

"Brit—wait, a crup, you say?" Harry almost opened his eyes in surprise. "What? Like the magical creature?"

He heard Lee shrug and shift around where he sat. "Not really. I mean, they're not actually magical, are they? They just have more tails than a muggle dog. And that's easily dealt with anyway."

Harry frowned. "Are you going to get rid of one of your tails to blend in then?"

Lee tsked. "Not sure. I mean, the Ministry guidelines for crup-breeds are pretty clear, so I thought it would be no trouble but…I'm really attached to my tails now, you know? I mean, they're mine."

Harry agreed. The two Harrys inside him would also protest against surgery. But it didn't take long for the excitement to fade and the conversation to come back to his vision.

When Fred's stomach rumbled, the pace of discussion increased.

"It seems we still don't know what's going on then," George had to exhale. "So, kiddo, I think we really do need to pass this over to an expert. Could you hire a private healer?"

"What, and wait three weeks for his first appointment?"

"True…St Mungo's, you reckon?"

Harry sighed. "I don't want it all over the papers, whatever it is."

"I mean," Fred spoke up. "We could try…Percy? You're close to him, aren't you Harry? And we found out over the holidays that he's not…I mean, he's got surprisingly hidden depths?"

Harry stifled a grin.

George tsked. "Bill or Charlie? I mean, it's not their specialities, but they both have some pretty esoteric knowledge and they'd be obliged to keep our secrets?"

"At least Percy's in England right now."

"Could your lawyer help out, Harry?"

"Oh, I'd rather keep him out of this actually. He knows…some stuff that he shouldn't also know with this."

The twins paused for a moment, which developed into a gap which Lee inserted himself into once again. "Uh…nothing pressing guys, but how are we going for time? It has occurred to me that we probably shouldn't have done this the midnight before school started."

"True," Harry began.

"Oh don't mind about that," Fred dismissed easily. "Harry's got a secret, he does."

Harry could just imagine George casually nodding next to him. "We can't break his trust, you see. Promised to keep it a secret, didn't we? But if Harry tells you himself now, well, that's another story."

Harry frowned. "Oi."

Theatrically, Fred gasped and, by the sound of it, thrust a hand against his chest to sway in betrayal. "Oh, Harry. After everything we've done for you?!"

"Fine, fine," he grudgingly agreed. "Just don't breathe a word to McGonagall."

"Will you be fine with it?" George suddenly asked. "I mean…what with your eyes and how you keep needing to throw up when you see things? When…when you 'move', for example?"

"Ooh," Fred muttered. "There is that."

Harry slowed his breathing again to calmly consider all the details he knew. The air against his skin was still cold, but a calming coolness now rather than the chill of before dawn. He tried to point his face into the sky because that seemed to help somehow. "I mean…I should be, I reckon. It's not like its magic, after all. It's just…well."

George offered. "…Time?"

"Yeah."

"Well," Lee finally offered up after it became obvious that nothing more forthcoming was going to be explained yet. "Worst case scenario, I don't suppose they'll put the Boy-Who-Lived in Azkaban, after all."

"Right," said Harry, as some dim laughter floated up from a Hogwarts floor far, far below them. "I guess that's it then. I'll go alone – Neville will take me up, if I ask, and you three will stay right out of it after all. I'll…"

He froze midsentence, halfway to standing and as unbalanced as being blind could make him. "Oh, brilliant!"

"What?"

"Madam Pomfrey will be fine. Padfoot, Prongs and the bastard were undiscovered all through school, so the medi-witch must not test for animagus things."

"I…huh?"

"Wait…you mentioned those names before, how do you know—?"

Harry's mind churned and he felt a burst of warm pride in his chest. If Sirius could keep his secret all the way through an Azkaban escape, there was no way that any prior Hogwarts nurse had ever had a hint of his nature. And what with all the trouble they got into, there was no way the Marauders had stayed out of the Infirmary for the last two and a half years of Hogwarts.

Harry felt a weight slide off his shoulders.

"You'll have to help me out, folks," he instructed instead, straightening and holding his arms out blindly. "Have we left anything behind? George, you'll need to take down your additional wards. Lee, could you sort out the cauldron please? Fred. Ah, I might need your help aiming my wand to take down the Fidelius, please."

There was a chorus of protests, but Harry waved them away. "It's time to go, I reckon. Crookshanks and Crow will kill me if I'm back late."

Fumbling, Harry patted down his robe front to find his mokeskin pouch and retrieved his wand from where he'd stored it safely; the arm holster had been a little more worrisome than he'd needed. "Am I pointing in the right place, Fred? Everyone behind me? Alright now, let's see this thing collapsed safely…"

It was quite the experience taking down such a complex spell with no eyesight; turns out you paid much more attention to how the magic felt lapping inside you. Odd sensation, that, now that it was all Harry could focus on.

And it was four minutes after that, when Harry tugged his golden chain out from under his robes and gestured for everyone to gather close. There had been some tugging and pulling and pushing, and George got choked once, but then everyone had the chain around their neck and Harry was turning the hourglass.

Harry was beginning to wonder if he could sense their positions a bit too well for someone who was blind, but decided to think about that later.

"I reckon one hour back will do us – no need to get me to the Infirmary before Madam Pomfrey wakes up. Or Neville; we'll just have him think I woke up like this. Hang on a mo, people…"

Then there was a blur, and they were back by an hour and just outside the edge of the Fidelius.

"How're we going in there, boys?" George asked curiously.

Fred craned to see. "Looks like you're about to wake up, Harry. I remember when I cast that spell, and it took a while for Lee to stop pacing."

Then they helped Harry down the stairs, step by step.

For one floor. Then they floated him.

The exhausted quartet were passing through one of the secret passages near to the Fat Lady's portrait when Harry, with only his head visible while the rest of him floated invisibly, slapped himself on the forehead and caused the knotted scarf to shake.

"Wait, what Harry?"

"It was the name thing."

"Huh?"

"My birthday party. Where they gifted me names," Harry explained, his voice rising higher as it all became clear to him. I…Merlin be damned. That would be my form too then! No wonder I wasn't a snake! Thank you past me!"

George dropped back to whisper madly to Lee, explaining why and how this had been a concern. Fred, his wand still out, hovered Harry back down to the ground and approached Harry instead. "I'm not sure what you mean, kiddo."

"Harry James Potter," Harry finally huffed out. "With 'Justus' to stay sane and righteous, 'Ambrose' to help me survive the year, and Merlin-be-damned 'Corbin' for cleverness." His mind felt slow and swollen now as everything fell together.

"The last of which, Fred, also helps make me the 'crow'."