Staring at the crazed Scabbers, Ron instinctively backed up against the wall, clutching his chest with one hand, and asked, half-hysterical, "What the hell is going on, can someone explain this to me?"
His pet of several years was suddenly using a wand—his mind was a complete mess now, and he didn't dare go near Scabbers at all.
"That's exactly what we want to ask." Professor Lupin glanced at the still-laughing Black, frowned, and said, "How do you know Peter can't change back?"
Kael didn't answer right away, instead taking out his wand.
"Stupefy!"
Peter, who'd been wrestling with his wand, immediately collapsed to the ground.
Only then did Kael return Hermione's and Professor Lupin's wands to them, and explained, "Because of those tonics I brewed for him."
"Tonics?" Hermione accepted her wand and frowned. "But nowhere in the books does it say pet tonics can prevent an Animagus from turning human."
"The regular kind can't." Kael said, "But I added a whole dried Mandrake Leaf to his tonic... and it was the one from the crown of the root."
"What did you say?" Professor Lupin blurted out, raising his voice instinctively.
Mandrake Leaves aren't cheap to begin with—one leaf costs five Sickles, and the one from the crown is even pricier, almost ten times the normal leaves.
That much money was enough for him to live on for a month, and Kael actually used it to brew tonic for a rat?
Did Kael actually know all along that Scabbers was Peter?
But that can't be... Professor Lupin shook his head. Only a handful of people had seen Peter's Animagus, and Peter's fake death was twelve years ago—Kael would only have been two? Maybe three!
"I suppose it was a coincidence..." Kael ignored Professor Lupin's odd expression and continued, "I just wanted the tonic to work better, never imagined he'd turn out to be an Animagus."
"But... what's that got to do with it?" Harry blinked, looking thoroughly confused.
"It's got everything to do with it." Kael conjured a cage, locked Peter inside, and answered without looking up.
He'd thought someone else would explain, but even after he'd finished with Peter, no one said a word.
Even Hermione and Lupin were just staring at him, totally at a loss, wearing the same blank expression as Harry.
"Don't any of you ever read any herbology books other than your textbooks?" Kael asked, almost automatically.
Hermione gave a slight shake of her head—among all the books she'd read, herbology books were the fewest.
Professor Lupin turned his head away too; he was in much the same boat as Hermione.
"Alright..." Kael sighed and went on, "Mandrake Leaves are a really useful thing for Fantastic Beasts—they heal wounds, boost constitution... Useful in tons of ways. But with Animagi it's a different story. You know the first step to learning Animagus, right...?"
The last bit was directed at Black.
"Course I remember." Black, floating in midair, didn't bother to ask how Kael knew he was an Animagus, just rubbed his sore jaw and said, "Hold a Mandrake Leaf under your tongue for a month... Honestly, that month was absolute torture. I nearly gave up so many times."
"Exactly."
Kael said, "The Mandrake Leaf records all the information about you as a wizard. It's like a second 'you,' or more like a beacon guiding you the way back..."
"A beacon?" Harry was at a total loss.
He felt like he was back in Professor Trelawney's Divination Class—completely clueless, just participating for the sake of it.
"Alright, I'll make it really simple." Kael sighed. "Greater Death's Head Hawkmoth cocoons let you transform from human to animal, while Mandrake Leaves let you change back..."
"What's a Greater Death's Head... Ow!"
Harry tried to keep asking, but before he could finish, Hermione elbowed him in the ribs, making him wince with pain.
"That's a Potion Material," Kael shot him a glance and went on, "So if an Animagus eats a bunch of Mandrake Leaves while in animal form, the 'wizard' information in the body gets dispersed, until eventually they simply can't change back."
"But that can't be..." Hermione frowned. "Professor McGonagall's taught us about Animagi; she never warned us about this. If it were really as dangerous as you say, there's no way she wouldn't have mentioned it."
"Because there's no need." Kael said. "Technically, 'wizard' information is very hard to disperse, unless you eat Mandrake leaves for years... and the moment you change back to human, it all comes back together.
There aren't many Animagi to begin with, and you'd have to stay in animal form for five years straight, continually eating things with Mandrake Leaves... The odds are just too low...
In a thousand years in the Magic Realm, there's only ever been one person... oh wait, now it's two."
Kael glanced at Peter in the cage.
Black started laughing again.
Professor Lupin looked at Kael and asked suddenly, "Did you already know Scabbers was Peter?"
Kael turned his head. "Why do you say that?"
"Because I didn't see any surprise on your face," Lupin said. "Whether it was me, Harry, Ron, or Hermione, we were all shocked to find Scabbers was Peter. But not you. You were just... calm."
At his words, everyone turned to look at Kael.
Ron looked like he wanted to say something, but Hermione stopped him.
"The reason I'm not surprised is that this isn't the first time something like this has happened." Kael shrugged.
"What?" Lupin was taken aback, as if he hadn't expected Kael to say that.
"Actually, in my first year, something similar happened. Another student's pet turned out to be an Animagus too—and a rat as well."
Kael grinned. "If you don't believe me you can ask Fred and George, or any of the students in fourth year and above—they all know."
Everyone exchanged confused and amazed looks.
Harry and the others all started Hogwarts a year after Kael, so they knew nothing about this. Lupin even less so—he'd only started this year, and what he did know about past events was all from other professors, and was basically all related to Harry.
He'd never asked about anything further back.
After Kael's explanation, Harry nodded, showing he understood... To be honest, if he saw someone with a second face growing out the back of their head right now, he wouldn't even be surprised.
Soon, the room lapsed into a long silence, with only Black's laugh now growing hoarse in the background.
Harry felt a little awkward. He hesitated, glancing at Professor Lupin, wanting to ask something, but not sure how to begin.
But his intention was written all over his face.
"You want to know about Lily and James?" asked Professor Lupin.
"Yes." Harry nodded. "I heard you say earlier—you used to be friends."
"The best of friends. At least for me, that's what they were." said Professor Lupin.
"Can you tell me, then?" Harry asked urgently. "What happened? And what did you mean about being a Secret-Keeper—what's that all about?"
Lupin hesitated a moment, but then nodded...
"Alright, you have the right to know the truth, though I only know the beginning. For the rest, you'll need Sirius to tell you...
Let me think where to start... The first time I met James and Lily was at school..."
...