The dungeon was in uproar. The students around Snape — mostly Slytherin thanks to the self-segregation of the houses — had gotten the worst of the splash and were all sprouting stubbly beards or shooting up a few inches too tall. Snape, who had gotten a face-full of the Aging Draught, had a funny little goatee and bleary eyes. He blinked around him rapidly, an expression of fury and confusion stamped across his stupid face.

A few cauldrons away, Sirius and James were howling with laughter, clutching their sides.

"Settle down, settle down," called Professor Slughorn idly from the front of the class where he was gathering an antidote. He didn't seem too concerned over his rapidly-aging charges. Sirius supposed that years of teaching adolescents to set things on fire permanently suspended one's sense of disbelief.

"It was Black, Professor!" Snape spluttered in a surprisingly deep voice. (James snickered.) "Black blew up my cauldron!"

"Don't blame me for your own shoddy potion-making," said Sirius with a contemptuous look. In fact, it hadn't been him. James had been the one to officially send the overheating hex to Snape's potion. Sirius had merely walked past Snape's cauldron for the sole purpose of attracting his attention and, undoubtably, his wrath. Per usual, Snape played his part perfectly.

"My shoddy potion making?" cried Snape in outrage. "My shoddy—" He didn't seem to be able to finish the sentence, his sallow features twisted in a furious snarl.

Sirius and James exchanged smirking glances. Remus was watching with a mild, interested expression, and Peter…Peter was exactly where he was supposed to be: darting into Professor Slughorn's private store cupboard under the cover of the pandemonium.

As Slughorn distributed little vials of the antidote to affected students, Snape continued his indictment. "Professor, it was Black. I saw him. He walked by my cauldron, and then it exploded."

Sirius arched an eyebrow. "A bit paranoid, aren't you? I didn't even have my wand on me. I know I'm hot, but I'm not that hot."

This comment proved to be too much for the group of Gryffindor girls behind him; they collapsed upon each other in giggles. Sirius noticed that girls often did that around him. He found the opposite sex to be a profoundly peculiar species. The only one among them who wasn't laughing was Lily Evans. Instead, she was giving him the sort of disgusted look most often reserved for a flesh-eating slug. He didn't mind though; infuriating Penny Prefect was nearly as much fun as infuriating Snivellus.

"Now, Severus," Slughorn placated. "These things can happen, especially when working with such volatile ingredients…boil the wormwood a little too long…"

"I didn't boil anything too long!" snarled Snape, but Slughorn wasn't listening; he merely patted him vaguely on the shoulder and returned to the front of class, just as Sirius saw Peter slip back into the dungeon. "I think that will do for today," their professor said, glancing at his watch. "We'll pick up on transformative serums next week."

The class began to file out into the stony halls, still laughing and gleefully reliving what had just happened. Snape remained glaring at his ruined potion as the boys left.

"Don't sweat it, Sniv, a bit of puberty will do you good," said James, giving him a jovial clap on the back.

Snape turned sharply, his expression murderous. "Touch me again, and I'll kill you."

James and Sirius exchanged an eyebrow-raised look. Sirius took a step forward. He towered over the skinny, sallow boy. Snape cowed a little, but returned his glare. "Big talk from a boy who needs a potion to grow a beard," said Sirius. He considered that greasy, miserable face for a moment, then flicked his thumb and forefinger against Snape's forehead, hard between the eyes. Snape flinched. "What are you going to do about it?"

Snape chewed his tongue. He seemed to be weighing his options.

"Come on," moaned James, rolling his eyes. For Snape was a distraction, and Sirius knew James had bigger prizes on his mind.

But Sirius couldn't restrain from calling, "Maybe you can brew a potion that will grow you a pair of balls!" as his friend dragged him off.

"Was that really necessary?" muttered Remus.

"Yes. Snape's a slimy git. Someone ought to remind him of it."

"Never mind all that," said James. "We've got important business to attend to."

"What are you—" began Remus, but he was interrupted by an angry voice from behind them.

"What did you do that for?"

Sirius turned to see Lily Evans standing directly behind him, arms crossed and using every inch she owned to give him a thoroughly dirty look. She still barely came up to his shoulders.

Sirius smirked. "Do what?"

"Don't play the idiot. I know you made Severus's cauldron explode."

"I did no such thing."

"Oh, please."

"You don't think it's remotely possible that your boyfriend Snivellus messed something up?"

"No," she said flatly. "I don't. Slughorn might let you get away with murder because of your surname, but the rest of us aren't stupid. And don't call him 'Snivellus.'" With an angry flounce of her dark red hair, she turned and marched down the hall, only to pause after a moment and shoot back, "And he's not my boyfriend!"

Sirius watched her go, feeling inexplicably irritated. Of course, she was right about Slughorn. They all knew it — they'd banked on the special favor he gave Sirius as a means of keeping themselves out of detention — but it annoyed him to be called out on it, particularly by someone like Lily Evans.

He still resented the Slug Club invitation. Slughorn had jovially chided him at the start of class for missing the dinner, and Sirius had played along as much as he could stomach, for need of the aforementioned special favor. But he hated it. When Horace Slughorn looked at Sirius Orion Black III, he did not see anything more than the glinting limb of a long family tree.

"Mental," said James, shaking his head.

It took Sirius a moment to realize he was referring to the retreating form of Lily Evans. Then James turned expectantly to Peter. "Did you get 'em?"

Peter proudly held out a handful of small, yellowing leaves.

James's grin broadened. "Jackpot."

"A month?"

"That's what it says."

"A whole month, sucking on a bloody Mandrake leaf?"

"It's right there, James." Sirius tossed The Infallible Animagus over to his friend. It landed on the carpet beside him with an accusatory flop. They were back in the common room, sprawled on the floor and going over their archives of Animagi notes. It was late enough that this was perfectly safe. The common room was practically empty, and Remus had long since gone to bed.

They'd been through every introductory book on Animagi the library had to offer, and they had the stacks of parchment to prove it. Finally, with the torturous riddle of a book that was The Infallible Animagus, they seemed to be getting somewhere. It just didn't seem like a very pleasant place to get.

James picked up the book and examined it for probably the hundredth time. "For in tandem the body and mind to enchant," he read aloud, "on your tongue must you keep a leaf of Circe's plant." He let out a groan of frustration. "I really hate this book."

"Circe's plant?" frowned Peter.

"Another name for Mandragora," said Sirius. "When the moon has waxed and waned…so we've got to keep it on our tongues for a month. A full lunar cycle. The text is very clear."

James snorted. He evidently felt there was nothing clear about The Infallible Animagus, but then James had never had much patience for ambiguity.

"And we're sure this is…you know…real?" said Peter. "I mean, the whole book is full of nonsense…"

"Yeah, but I told you, Pete, it's not," said Sirius impatiently, "It's like…it's old magic. Earth is earth…but earth is stone…stone is dust…I don't know how to explain it to you, but it makes sense, all right?"

"It's saying everything can be anything else," summarized James. "Everything is in flux all the time, everything is transfiguration. Change is the eternal constant, and all that. Old magic, like Sirius said."

"Okay," said Peter, though Sirius was fairly confident all of that had gone right over his head, "but what does that have to do with Mandrakes?"

"Well, it's all about accessing that old magic, isn't it?" said Sirius, stretching out his limbs as he repositioned himself on the floor. "If everything is transfiguration, then everyone already is an Animagus. That's why you don't get a say in what kind of animal you become. It's already there. The preparatory spells, the Mandrake leaves…it's just about lowering the physical boundaries to allow that change. Mandrake leaves are often used for transformative serums, it makes sense they'd be used for a spell of this magnitude…since it's not even really a spell, it's a whole self-transformation thing. You never un-become an Animagus, after all."

"You sound like a bloody textbook," said James fondly. "I don't know whether to be proud or annoyed."

Sirius rolled his eyes. "Well, I've only had to listen to you prattle on about this rubbish for three years. Anyway, it says right there that you've got to keep the leaf of a Mandrake in your mouth for a full lunar cycle."

"Have you ever tasted a Mandrake leaf?" asked Peter curiously.

"No, have you?"

"Yes, don't you remember when you dared me during Herbology second year?"

James let out a loud, reminiscent laugh. "Oooh yeah. That was a riot. You nearly threw up…oh."

"Got there, have you?" said Peter with grim satisfaction.

There was a pause as the three boys digested this unpleasant revelation.

"Well, shit," said James.

"The Mandrake leaf looks like the easiest part," said Sirius, reclaiming the book and flipping through its pages. "The rest is…well, weird."

"Weirder than sucking on a Mandrake leaf?"

"We've got to meditate."

"…Meditate?"

"Yup. A mind in three parts. Apparently you've got to be able to separate the animal mind from the human mind from…the physical form, I guess. And that's where things can go wrong: If the animal mind takes over, then you could either lose the ability to change back into human form, or you could remain in human form but have an animal mind."

"Oh, bloody hell," said Peter.

James frowned and pored over the piles of parchment once more. "Meditation. All right. Everything else it looks like we've done. I mean, all the pre-transfiguration spells were in the other books. We've mastered those. Now it's just a matter of the Mandrake, the meditation, and…learning to do it without a wand, I guess."

Peter's laugh was a tad shrill. "Oh, that's all? That'll be a breeze."

"Hey, how about a little optimism?" demanded James. "We've made it this far. We're so close, I can almost taste it."

"Does it taste like a rotting bubotuber?" said Peter. "Because that's all you're going to taste for the next month."