'What an insolent, horrid, nasty-"

Severus was running out of the vocabulary needed to explain exactly how he felt about one Harry James Potter. Soon he may need a dictionary to find more words to insult the boy, because he wasn't finished with his ranting just yet.

-conniving little cretin of a boy!"

Conniving. Now that was a new one. And when the word slipped from his mouth it sounded surprised...and almost, slightly, approving. Almost.

For the Potter boy had managed to do something he never thought anyone could;

He'd unknowingly twisted the arm of one big, scary Potions master.

To say Severus was shocked by the boys request earlier that morning would be an understatement. A very big one at that.

And he, disguised as Hydrus, had voiced that.

"What happened to 'your secrets safe with me' ?" He's said after recovering from the shock of the ridiculous request, as-well as the name-calling. 'Fins?' He thought, mentally scoffing, 'is that really the best he could come up with?'

Though, let's not forget, he'd called the boy "twig legs" not too long ago.

"Oh, It still is" the boy had reassured him, still looking far too pleased with himself, "And it will be...if you teach me how to swim"

Blackmailing. How very...un-Gryffindor of him.

"I think it's quite a fair bet" Potter had said, and Severus bared his razor teeth up at him in annoyance, "you teach me the basics of swimming, and I keep you hidden from the school"

That was not a fair bet at all.

Severus had been ready to jump right out of the water and throttle the boy, and then proceed give him a piece of his mind. Tell him just exactly how he felt about the frankly absurd request. And then, of course, to inform him that he would never in all his years left on earth even think about entertaining the boys childish requests;

Granted, none of that happened. No.

Instead; He said yes.

An idiotic thing to do, sure, but nevertheless he'd done it. He hadn't really much a choice otherwise. For all he knew, Potter could very well be a nasty little snitch. And he very much would like his "secret" kept just that. He shuddered to think of it getting out to anyone else. The consequences of that could be far worse than he imagined.

Therefore, He had no other choice but to trust that the boy would keep it, if he too kept up his own side of the bargain.

He watched Potters face brighten upon his agreement, face cracking into a huge smile- he'd even bounced up and down on the balls of his feet; the epitome of pure joy. It only served to annoy Severus more. 'Just you wait till our next potions class, Potter' he thought, 'I have a three foot essay on "the properties of minding your own goddamn business" with your name written ALL OVER IT'

He could secretly get his own revenge back, he surmised, as he grudgingly watched the boy bid him farewell- promising to be back for their "swimming lessons" the following morning. "You better be here too!" He had called, before scampering back up towards the castle.

He could find excuses to give the boy the worst detentions imaginable. Although, would that be a punishment for him too? Having to endure the boys company for longer than necessary. It was bad enough as it was, he needn't more time spent with the boy than he already had on his hands. Or rather, will have on his hands come tomorrow morning.

He later pondered over their deal, mulling the idea over a large tumbler of Firewhisky and reclining peacefully in the chair of his private quarters. Now, in his regular form- as Hydrus couldn't survive long out of the water before dissolving back into Severus Snape.

It most probably wasn't nearly as bad as he was making it out to be. In hindsight, teaching the boy who lived how to swim might be actually be a necessity. A quality skill to have, if ever were the Dark Lord to return. After all, If the Boy truly couldn't swim a stroke (which Severus knew was very likely given the theatrics the other day in the lake), all the dark wizard would have to do to defeat him was throw the boy into a large puddle. Done. A Simple, yet highly effective murder.

Severus chuckled to himself at the silly image, before putting his glass down. That was probably enough alcohol for one evening if the idea of Harry Potter flailing about in a shallow puddle was reducing him to a state of laughter. He had more composure than that.

So he retired for the night, finding a will to sleep, and dreading the very next morning where he'd be forced to teach Harry Potter the basic steps of swimming. Or maybe, they'd start out even simpler than that;

Floating.

————————————————————————————————

"Good morning!" Harry greeted the merman, spotting the top of his head just poking out the water a few metres out from the shallows. Imperceptible to anyone stood further away than where Harry currently perched on the waters edge.

And morning it was. Six o'clock to be precise, the sun having barely risen up into the sky. Stray cusps of sunlight still danced on the horizon, casting pretty colours onto the lakes surface.

Harry marvelled at it, clutching his towel and spare clothes tightly to his chest and breathing in the cool morning air. Then, he popped them down on the rocks beside him, and started to unfasten his robes.

"Not entirely a 'Good' morning" he heard Hydrus grumble when the merman swam closer, head and shoulders out the water. "I often prefer my mornings free of human children"

Harry ignored the scathing comment, opting for a humorous retort, "'guess you'll just have to get use to me then" he shucked himself out of his robes completely, the borrowed swimsuit hidden beneath them now fully visible. It was one of those full body ones, and reminded Harry of those muggle swimsuits that surfers wore. It fit him quite nicely actually, considering it wasn't tailored for him.

Hydrus scowled in reply, though Harry noticed it went away quickly, replaced with something akin to a smirk.

"What?" The boy asked.

"Nice colour" the merman said, gesturing to the swimsuit, which was a mix of black, silver and Green.

Slytherin Green.

Harry frowned, "I hate green"

"I think it suits you" and it was the truth. As much as Harry may loathe the colour, he suited it very nicely.

"Reds better" said the boy with such delight you'd think it were a fact, "these are slytherin colours. But it was the only costume that fit me"

"Hm" was Hydrus' bored repsonse, thought Severus was secretly surprised by the boy. Kudos to him for choosing practicality over silly house rivalry.

Harry chatted idly as he pulled his shoes and socks off, putting them next to his other belongings, "I'm a Gryffindor- our house colour is red. We're the best house by far". He plucked his glasses off of his face at the last moment, almost forgetting he couldn’t take them into the water with him.

Hydrus rolled his large- entirely black- eyes. "I don't really care" he said, "now hurry up and get in. I haven't got all day"

Harry went quiet, looking down at his now bare feet, shuffling them back and forth across the wet pebbles. He inched closer to the shallows, but didn’t make a move to get in just yet.

“Is it cold?” He asked, shivering when a soft breeze brushed past him.

Hydrus sighed, “I assure you, it is much warmer in here than it is out there”. This was true, as the plantation on the lake beds gave off heat, warming the water in its colder months.

He watched as the Potter boy dipped a toe in, testing the waters for himself. Severus inwardly snarled, did the boy not believe him?

He glanced back up at the merman with a squint, and saw him floating a few metres away from him and looking very impatient. “Is it deep?” He asked, aware that the mans (man? Harry figured since Hydrus was male it felt right to still think of him as a man...right?) body was fully submerged.

The “man” in question did not look amused at all by the boys questions. “We’re in the shallows” he deadpanned, “My tail can still brush the bottom of the Lake here. But the water gradually becomes deeper the further out you go”. Good Lord, Severus felt like he was explaining himself to a five year old, never mind a boy of Eleven.

“Is it-“

“Enough with your incessant questions!” Hydrus finally snapped, Startling the boy into silence. “Just get in the water so we can be done with your silly lesson!”

Harry, slightly hurt from the ‘silly lesson’ comment, and feeling much like he was being told off, hurried to comply- though his pacing was probably still exceedingly slow to the merman’s standards. “Sorry” he said, his feet disappearing under the water as he nervously baby-stepped into the lake. “I’m just nervous. I don’t like the water”

“So you’ve said. Quite often, actually” Hydrus replied, shaking his head, long black tendrils of hair sticking to his shoulders. His hair was much longer as Hydrus than it was when he was Severus, reaching almost to his waistline. This annoyed him often, as it only served to get in his way. He peered up through the long, wet curtains of his hair at the boy, edging closer when the first year failed to move quicker into the water.

“Y’know” the boy huffed, stopping when he found the very edge of the shallowest part of the lake, little toes clinging to the the large flat rock before the clay beds dipped into a deeper section of the water. “Your pettiness won’t make me move faster”

“Water. Now”

“Okay! I’m going, jeez!”

But he wasn’t ‘going’, in fact, he was barely moving at all. The boy slowly tried sitting down on the rock, his goal to shuffle his way into the deeper part instead of jumping the rest of the way in.

That was the exact point where Severus had enough. In a flash, the merman had swam the rest of the distance between them, grabbed him by the wrist and tugged the boy towards him.

The effect was immediate.

Harry yowled as if he’d been hurt, panic seizing him by the throat and sparking a chill across his body that had less to do with the water and more to do with the shock. He flailed about out of instinct, trying to stay afloat, water splashing into his eyes and making him more hysterical.

Without thinking, Harry clung to the first thing he could find- which so happened to be Hydrus. Within seconds, his arms had snaked around the merman’s neck and his legs fastened about his waistline. Harry held tightly to him, gasping for the breath he couldn’t seem to find. The mermaids skin was cold to the touch, but smooth, as were the scales Harry could feeling brushing against his feet as his tail swished back and forth in alarm.

“What the-“

Was all Severus managed to say before he had an armful of first year Gryffindor, shaking like a leaf and whimpering into his shoulder.

He was stunned, frozen in place whilst the boy decided to use him as a makeshift life-jacket.

It took him a while to find his voice, “this is ridiculous, remove yourself from me now!”

Harry tried to reply, but the words caught in his throat, all he could do was stutter out a harsh breath. His panic increased tenfold when he felt webbed fingers trying to pry his arms from the merman’s neck. “No!” He cried, “please! I’ll drown!”

He felt rather than heard the man scoff, voice sounding a lot harsher from the close proximity. Like stones dragging across concrete. “Don’t be silly, You most certainly will not”

“Yes I will” Harry murmured, still not relinquishing his hold on the man, staring into space over the mans shoulder where he rested his chin and forced himself to do nothing but breathe. “I can’t stay up on my own”

Severus, feeling slightly awkward, paused trying to tug the boy away from him, simply resting his clawed hands on the boys forearms, not failing to notice the goosebumps littering the boys skin. A response to his fear no doubt, as the water wasn’t exceedingly cold.

“You will not drown” he said, voice slightly calmer yet still stern. “I’ll have a hold of you”

The boys voice was quiet when he next spoke, and Severus didn’t bother to suppress his eye roll.

“Promise?”

“Yes. Now I will not repeat myself again; remove yourself. Your childishness is becoming tiresome”

A few moments later, he felt the boy shift, slowly retracting himself from the mermaid, still cautiously holding onto him- though his grip was far less suffocating than before.

True to his word, Hydrus did not let his grip waver on Potters arm, and continued to hold onto him as he lowered himself into the water, till only his head stuck out from its depths. He elected to ignore the small, scared noises that escaped the boy as he did so, simply grateful that the boy had eventually let go of him.

“There” the boy finally breathed, before craning his neck to frown up at him- seemingly feeling gutsy once more. An almost laughable image to Severus, who not a moment before had the boy clinging to him like his life depended on it. It seemed a Gryffindors bravery only came about when they deemed fit. “Happy?” Harry asked, none too nicely either.

It was Hydrus’ turn to scowl. “Lose the tone, or you can forget your lessons” he said, half tempted to let the boy go, scare him out his wits a little longer. He didn’t, and the boy was thankful for that- he sensed it in the way Potter suddenly grew quiet, ashamed.

“Now. Let’s begin with treading water” he said, and very slowly loosened his hold on the boys arm- still not letting go completely, but that fact didn’t matter to Harry, who began to panic once more.

“Wait!” He cried, kicking his legs, causing the water to stir, “you said you wouldn’t let go!”

“I’m not-“

But his words fell on death ears, for Harry’s breathing had become ragged again.

“Mr Po-“

“Please don’t let me go! I promise I’ll stop being cheeky-“

Harry suddenly yelped in shock when a large black claw reached out and flicked him sharply on the forehead. It didn’t hurt, but it certainly knocked him out of his frenzy. He looked up at Hydrus, who remained permanently annoyed with the boy. “Ow?”

Hydrus sighed, “Dear god, Twig legs” he began, the nickname beginning to stick. “do you want to learn or not?”


“...yes?”

“Then you’re going to have to use those things on the side of your head" he says, lightly tweaking one of the boys ears with the same black claw, "and start listening to me"

"Okay, I'm listening now"

Hydrus seemed unsure, giving the boy a long, quizzical look. He still seemed fidgety. He hadn’t seen anyone this nervous of the water since...well, since ever. The boys chest was still rising and falling dramatically, trying to suck in as much oxygen in the air as he could. Hydrus shook his head just watching him. It’d take a miracle to teach this boy to swim. But he had to start somewhere;

‘Let’s try the beginning’

“Breath” he said, gaining the boys attention instantly. “Breath control is a very important part of swimming. Without control over that, the rest is near impossible”

“It is?” The boy asked, chest still rattling as the air struggled to slip in around his words. The man nodded, big black eyes glinting down at him- still terrifying to look at, yet presently remained neutral in their glare.

“Focus on your breath for a moment. Don’t think of anything else” he said, and the boy did as he was told. Even going as far as closing his eyes to block out any other distractions. “In and out. Slowly”

Finally listening, the boy followed his words- breathing in time to the mermaids helpful words. After a while, Harry noticed- or rather didn’t notice- that everything else began to slip away, even the sensation of the water around him. Only his breath remained- strong and steady in his chest.

“Good” he heard Hydrus say, and the small praise made Harry smile despite himself. It was enough to ground him to the present, where he blinked his eyes open to peer up at him.

Harry noticed the corners of the mans mouth tugged up into a barely noticeable smirk. “What?” He asked innocently, brows pulled tight together in puzzlement, “what is it?”

Hydrus said nothing, instead he held up two webbed hands in front of the boys face. He watched the confusion melt away as the gears in boys head clicked into place;

“You’re floating”