During the rest of the Christmas holiday, it only took Cohen one afternoon to prepare a breathing apparatus for Harry to use underwater.
It looked like a fishbowl flipped over his head, and the effect was almost identical to the Bubble-Head Charm, making Cohen regret spending even that much time crafting something so utterly pointless.
At the end of the holidays, after Saturday lunch, Cohen pulled Harry into the Room of Requirement to show off his handiwork.
"If it looks and works exactly like the Bubble-Head Charm, then…"
Harry, who had been failing to master the spell for three days straight, started to waver.
"…why am I still trying to learn a spell I have zero confidence in mastering?"
"Because once we're in the lake, no one can see what's happening underwater," Cohen replied.
"All they'll see is one champion diving in with a gadget on his head, and four others diving in with just their wands. You'll be the example of what not to do—though technically, the rules don't say you can't use props, so it's not against the rules."
"Sounds like the kind of thing people won't shut up about for years…" Harry muttered, already imagining the whispers and laughter.
"If you don't use it, then I really did waste an entire afternoon," Cohen reminded him, though he agreed the whole effort felt rather pointless.
"So that's why I've been struggling!" Harry accused him jokingly. "You set me up!"
"Of course," Cohen nodded solemnly. "My middle name is Capitalism."
Despite his strong desire to do things the right way, Harry couldn't help being tempted by the path of least resistance. Even a good kid like him couldn't entirely resist the lure of an easy win.
But Cohen didn't have time to joke around today.
Niccolò had reminded him that the "Humanity" he'd been cultivating might finally be ready.
After sending Harry off to the common room with his fishbowl helmet, Cohen pulled out the Hermes Flask that contained the growing fragment of humanity.
Inside, the substance had condensed into a sticky, bluish-green slime — something like a Flobberworm that had melted and gone stiff.
"You're actually gonna eat that?" asked the Earl with a wince. "Ugh…"
"Then maybe I won't," Cohen replied flatly.
"No, no—don't back out!" the Earl scrambled to stop him. "You don't want to turn into a cold-blooded, kill-on-sight supervillain, do you?"
"I already kill without blinking," Cohen muttered, examining the sludge. "Looks like it's matured… or maybe it died."
He remembered it used to be a misty cloud — tiny, strange, and almost appetizing in a weird way. Now it just looked revolting.
Really, everything's cuter when it's small.
"So?" The Earl leaned in curiously after Cohen downed the substance in one gulp. "Feel anything? Like, do you not want to torture people anymore?"
"Shut it," Cohen shot back. "It's not like I used to wake up every morning craving murder. There is a bit of a change, though… subtle."
"What kind of change?" the Earl asked.
"The more I look at you," Cohen murmured, "the more I remember all the time we've spent together. And the more I remember…"
"...the more you realize I've always been good to you!" the Earl beamed. "Go ahead, say I'm the best owl ever—then give me a—"
"Don't flatter yourself," Cohen cut him off. "The more I remember, the more I want to punch you. Did you think this was some kind of 'good guy potion'? Drink it and poof, you're a saint?"
"Niccolò! Your flask is defective!" the Earl shouted. "This guy's becoming less human by the minute!"
But contrary to the Earl's opinion, both Cohen and Niccolò believed the experiment was a success — at the very least, Cohen had returned to his first-year habit of plucking all of the Earl's feathers whenever he got mouthy.
"You evil, conniving, bloodthirsty little Dementor!" the Earl screeched, trembling with rage. "Still holding grudges, huh?"
"If I really held grudges, you'd be bald another seventy or eighty times over," Cohen replied.
"Remember that astronomy assignment? I told you not to use blue ink."
"Yeah, and using blue ink turned out to be right!" the Earl huffed. "It's not like you lost anything."
"That's only because I predicted you'd pull a stunt like that," Cohen said proudly. "You've got the world's most predictable contrarian streak."
"Disgusting. All you ever do is scheme against owls." The Earl puffed up, scandalized. "I'm filing a complaint for animal abuse!"
"Please. If you didn't secretly like it, why not use a counter-spell?" Cohen asked, seeing right through him. With a flick of his wand, he restored the owl's feathers. "You're just a weird old owl with a bizarre kink…"
"AAAHHHH!" The Earl shrieked and dove at Cohen's head, flapping furiously.
---
Cohen's first Christmas at Hogwarts had been unusually peaceful — so much so that, come Monday, he still felt like he was on break.
In Charms class, Professor Flitwick was teaching the Banishing Charm — the polar opposite of the Summoning Charm. Instead of calling objects toward you, this one flung them away.
Every desk had a pile of cushions to avoid injuries from flying furniture. But Cohen and Harry's desks sat completely undisturbed — they'd been given special permission to practice spells related to the Triwizard Tournament instead.
Harry was still working on his Bubble-Head Charm, only now he was practicing on a mouse in a fishbowl rather than himself. (The poor creature had been rescued from the Earl's clutches.)
"At least it's stopped choking underwater for three extra minutes now," Cohen observed. "At this rate, you'll last an hour underwater in twenty days."
"But didn't you already prepare everything?" Ron asked, having wandered over during a break from his own practice. "Why are you not doing class either?"
"Wouldn't you take a free pass if you had one?" Cohen whispered, glancing around to make sure Professor Flitwick didn't hear.
Not that it really mattered — the professor seemed too busy dodging objects flying around the room, including himself.
"Sorry, Professor!" Neville shouted, panicking. His aim was still wildly off.
In the end, Flitwick had to personally stop the chaos with his wand.
Though dazed, he didn't seem particularly mad.
"Next time, aim before casting, Mr. Longbottom…" the tiny professor mumbled.