There was something wrong with the Potter boy.

Severus glared down at the Gryffindor table, his eyes scanning for the source of his irritation. Potter was nowhere in sight, something which Severus had come to expect over the course of the first fortnight of the autumn term. His eyes fell instead on Potter's entourage, who were conversing quietly and shooting anxious glances at the spot reserved for their third member.

It was just like Potter to cause everyone to worry, Severus griped to himself. He was probably skipping breakfast for attention, given that he'd now spent two weeks away from his adoring relatives who doted on him and pandered to his every whim.

Yes, that must be it.

He'd only agreed to keep an eye on the brat as a favour to Albus – although why the meddling old man couldn't just ask the wolf, or someone who actually liked the boy, was utterly beyond him. His objections had fallen on deaf ears, and now he was stuck on what he liked to refer to as 'Potter duty'.

He hadn't been expecting it to be an easy enough job. Not when he was tasked with making sure the miscreant didn't get up to anything. But he'd been anticipating the boy would roam the castle at all hours, or go hunting for Black, or perhaps perform some equally stupid stunt in order to get more admiration and praise from his dim-witted peers. He'd even spent the three days between agreeing to Albus' ridiculous request and the brat's return eagerly plotting the detentions he'd hand out when Potter inevitably started causing trouble.

Instead, the boy had turned up pale and lifeless. At first, Severus had suspected a ploy for the pity and concern of his peers. In fact, he still thought that was the most plausible explanation for the brat's behaviour .

But he could not shake the nagging whisper in his mind… Two weeks had now passed since the students had returned to the castle, and Potter only seemed to be withdrawing into himself more.

Severus had tried to ignore him. After all, he'd only agreed to make sure the boy didn't come to any harm, not babysit the brat and discover what trifling teenage drama was wounding his pride. But the boy was an enigma; and try as he might, Severus couldn't ignore him, for there was nothing he hated more than an unsolved puzzle.

And – although he would never admit it even on pain of death – he was beginning to worry about the boy.

Severus glowered at the empty seat next to Granger once more. What was the world coming to, when he couldn't even enjoy a Potter-free meal in peace? He shook his head, and determined to forgo thinking about Potter for the rest of the meal, lest it ruin his appetite.

But alas, fortune never seemed to favour Severus, and the Potter brat shuffled into the Great Hall just as the professor had finished buttering his toast, once again forcing his attention away from his meal. He glared at the boy in disdain, noting as he did so the heavy shadows under Potter's eyes and the awkward movement with which he walked.

Maybe he was just tired from roaming the castle after curfew and causing mayhem. Perhaps Severus had missed him lurking about the previous night – perhaps because he'd used that damnable cloak. Maybe he wasn't eating because he'd snuck into the kitchen and devoured all the sweets the house elves would give him.

And maybe this year would reveal Longbottom to be a gifted Potioneer.

Severus sighed loudly, drawing the attention of Professor McGonagall, who was seated his left.

She followed his gaze, her lips thinning as she recognised the object of his scrutiny. "And what has Mr Potter done to draw your ire this time? He's been here all of two weeks, he can't have caused you much trouble yet."

Severus tactfully didn't point out that the words 'much' and 'yet' served only to prove his point. "Never underestimate Potter. You look away for one minute, and he's off fighting trolls or blowing up cauldrons or sneaking into the Forbidden Forest and causing chaos."

Minerva frowned reprovingly at him. 'He's not his father,' she reminded him. "He doesn't seek out trouble-"

"And yet, trouble always seems to find him," Severus interjected dryly.

She glared but didn't respond. Severus smirked, rewarding himself with another bite of toast. He turned to his right instead and struck up an easy conversation with Flitwick about the merits of Hector Vance's latest modifications to the Oculus Potion.

All the while, he could not help his gaze from flickering now and then back at the boy. While he'd made it through two slices of toast, Potter had merely nibbled at his own breakfast. Severus watched as he took a forkful of scrambled eggs in what was clearly an effort to appease Granger, barely bit the corner of a piece of toast, and moved the remainder of his food awkwardly around his plate. He frowned. Next to him, Minerva cleared her throat again.

"Potter looks … peaky today," she murmured, as Flitwick's attention turned several seats down to answer a query from Professor Burbage. She frowned, both of them watching now as Potter mutilated the food on his plate without consuming another mouthful. "You have him next Severus, do make sure to keep an eye on him."

"The last thing Potter needs is more attention," Severus griped, pretending that he hadn't spent the last two weeks carefully noting Potter's abnormal behaviour.

Minerva continued as though he'd never spoken. "I suspect the poor lad is worried about Black. Merlin knows how he must feel. The Minister wouldn't even let him stay in Diagon Alley after that dreadful debacle for fear he'd be attacked. The boy must be worried sick, knowing that Black's on the loose… Not that he knows anything about Black's connection to his parents, of course. Minister Fudge was quite careful not to let that slip. But just knowing that there's a Death Eater on the run who's looking for him is a heavy burden for a boy his age to bear."

Severus rolled his eyes, "Yes, poor Potter indeed. It must be so hard for him to spend an extra two weeks with his doting relatives, being waited on hand and foot and having his every whim catered to, rather than a fortnight roaming around Diagon Alley and being bowed to by every insipid shopper in Britain. It must be so difficult for the poor boy."

The familiar distain felt much more comfortable than this new, unsettling concern. Severus revelled in it as he glared at the back of the dark head.

He was spared Minerva's scathing retort by the ringing of the five-minute warning bell. Hundreds of feet suddenly took to the flagstones, students and teachers alike jarred from reverie and food into their usual morning scramble.

How he loathed Tuesday mornings, Severus thought bitterly as he dared a group of Hufflepuffs with his eyes to attempt to cut across his path to the door. Every year, he begged Albus to pair the Gryffindors with anyone but his Slytherins. Every year, his request was cruelly denied. The headmaster maintained his sadistic insistence that the two houses would one day get along; and the foolish belief that Severus 's sanity would survive the intervening years before that magical day arrived.

The Hufflepuffs stepped out of his way, gulping. Taking a deep breath to prepare himself for the horror he faced, Severus stalked out of the hall.

As he walked through the cold, stone dungeon, Severus mulled over the conversation he'd just had with Minerva.

Maybe the problem with Potter was Black. Knowing a mass-murderer was on the loose and hell-bent on murdering you would no doubt prevent any thirteen-year-old from sleeping. Even if that thirteen-year-old was Potter - who'd spent the last two years knowing that a different and even more dangerous mass-murderer longed to kill him. Perhaps fear had sapped his appetite.

Or perhaps the brat was acting out because he was not to be allowed to run wild in Diagon Alley.

The limp, Severus supposed, Potter could've got anywhere. Perhaps he'd been roughhousing in the Gryffindor common room. Perhaps he'd fallen off his broom. Perhaps he'd been creeping by Mrs Norris after hours and tripped over his own feet.

Except if that were the case, why did Potter seem to be attempting to conceal it? Potter was just like his father… and James Potter would never have squandered an opportunity for fussing and pampering from his doting entourage.

His miniature was just the same, Severus knew. He grimaced, feeling almost sick in memory of the towering pile of gifts left by Potter's adoring fans after the brat's escapades in his first year; or the near equally obnoxious haul that had graced his bedside after his Quidditch mishap in his second. Surely Potter wouldn't miss out on any opportunities for sympathy, especially not if he was in pain.

And yet… the very fact that he was still attempting to conceal the limp suggested not only that he had not told his little friends, but also that he had not yet sought the Mediwitch.

Severus pinched the bridge of his nose in irritation, wondering for the thousandth time why he didn't just pass the problem off to Minerva, and let her worry about the boy. Wondering why he could not seem to silence the niggling voice in the back of his head that demanded he look into it further.

Scowling, he rounded the corner to find his snakes standing together opposite the Gryffindor students in the corridor. Most were smirking, as Malfoy mimed a swooning fit Severus had already seen at least a dozen times in the Great Hall since the arrival of the Hogwarts Express. He took note of Potter's clenched fists and Weasley's red ears, and refrained from rolling his eyes with immense difficulty.

"In. Now." He barked at the lot.

Just one lesson where the students weren't at each other's throats. That was all he wanted. Just one.

He waited for them all to file in, glad to find that even his Slytherins had fallen silent at his obvious impatience.

He swept in after them, closing the door with a bang. All thoughts of Potter were banished from his mind as he surveyed the students in front of him, who were quietly unpacking their potions kits and getting out the rolls of parchment he'd demanded on Hair-Raising Potions.

He summoned them with a flick of his wand, mentally taking points from Brown for using purple ink, and started his lecture. Out of the corner of his eye, he could see Malfoy throwing puffer-fish eyes at the back of Potter's head, clearly disappointed at the boy's lack of reaction.

Severus frowned at the apathy – just for a moment. Then he purposefully turned his head away, determined to banish all thoughts of the boy from his mind, and focused on explaining the properties of ginger roots to the third-years.

Despite his vow to ignore the Potter boy, Severus couldn't help but watch him out of the corner of his eye as the lesson drew on.

He noted how the child staggered when he rose to grab fresh ingredients from the storage cupboard, having destroyed the first set. He watched Granger lean over and take the Flobberworms from his grasp, dicing them efficiently while Potter just sat there, staring into the cauldron with an indecipherable look on his face.

Not that Granger didn't always pick up the slack for Potter and Weasley… but this was excessive even for her. She was keeping an eye on Potter too, Severus noticed, and her expression only seemed to grow more anxious as he listlessly stirred the potion with a vacant glaze to his eyes.

"Remember Harry, it's two anticlockwise stirs followed by thee clockwise," she whispered. "If you just stir it clockwise, then the fluxweed won't mix properly with the jobberknoll feathers and the whole potion will be destroyed."

He nodded apologetically at her, and moved his focus back to the stirring without any visible increased focus. Granger shared an anxious glance with Weasley, who leant over the steaming cauldron to whisper something to Potter. Severus could feel his own agitation boiling at what was, even for Potter, appalling lack of effort.

He paused by Longbottom's cauldron to berate him for his usual incompetence, and then moved closer to where Potter and his sidekicks were sitting, intending to admonish him for his lack of focus…

BOOM!

The noise reverberated around the classroom as Potter's cauldron exploded spectacularly, dousing the room in an acidic green substance.

Severus stalked furiously to the offending work station, assessing the room for damage as he did so.

"Mr Potter," he began in a deadly tone, the room falling silent, "Your arrogance never fails to astound me. I suppose it is too much to ask a celebrity like yourself to pay attention to your work, rather than leeching off Granger and lazing about! You have put the entire class at risk with-,"

He stopped midsentence, horror replacing disgust as he considered the green slime more closely. He had been about to sneer that the substance could hardly be considered a potion – let alone the Shrinking Solution he'd demanded today. But he recognised the noxious and highly flammable vapours which were seeping out of the remains of what once had been a cauldron.

Only Potter.

"Everybody out!" he yelled furiously, already setting up wards around the former cauldron in an attempt to contain the fumes. "Await me in the corridor."

"NOW!" he roared, when they failed to react immediately.

There was a sudden stampede for the door, many of the students leaving their bags behind in their haste to escape the classroom.

Severus banished the remains of the cauldron as soon as the room had cleared. He cast several air filtering spells in quick succession, which were second nature to him after more than a decade of teaching incompetent children.

By the time he had ensured the classroom was safe, the lesson period was nearly over. Even so, Severus summoned the class back in to collect their bags and, more importantly, to assign them four feet on exactly what Potter had done wrong. He ignored Malfoy's melodramatic complaint, along with the rest of the impertinent mutterings, and dismissed the lot exactly two and a half minutes early.

"Potter. Stay behind," he barked, as he saw the boy attempt to slip unnoticed out the door. "Granger, Weasley, off with you."

Potter turned with a grimace. His shadows hovered at the door. "Ten points from Gryffindor," he spat at them. "And it'll be detention too if you two don't go to your next class. Now."

Granger tugged Weasley out of the classroom reluctantly. With a flick of his wand, Severus shut the door firmly behind them. He moved behind his desk before glaring at Potter.

"Sit," he said venomously, motioning to the empty chair in front of his desk. Potter dropped into it with a gulp and stared at his hands. Severus slammed his own onto the desk's surface.

"Look at me when I'm speaking to you, Potter," he growled, though noting Potter's flinch. "While I'm aware you hold little concern for anyone but yourself, your arrogance today remains astounding. Too lazy even to pay attention to stirring, after passing off the entirety of the preparatory work to Granger. Too busy day-dreaming to have an ounce of concern for your fellow students! It's disgraceful Potter, even for you."

He glared down at the boy in front of him. The spark of defiant anger that met him was the first sign of life Severus had seen from the boy in days. He found the thought oddly comforting… not least because it fed his own familiar fury with the brat.

"Detention. Seven o'clock this evening. Now get out of my sight."

Potter wasted no time in exiting the classroom, flinging the door ajar so that it banged off the wall as he made his escape.

Severus scowled after him, all thoughts of concern for the brat finally banished as he looked around the carnage of the room. Not for the first time, he wondered what he'd done to deserve having Potter and Longbottom in the same Potions class.

Frowning again in disgust, he summoned a house-elf to clean up the remaining mess and moved swiftly of the room, desperate to indulge in some well-earned peace and quiet in his office during the next period – which, mercifully, he happened to have free.

He was in no mood for interruptions. Yet as he stalked down the corridor, the unmistakable sound of shouting students echoed from the opposite direction. He changed direction with an audible sigh, already plotting the detentions he'd hand out to whichever idiots had the audacity to hurl insults at each other rather than attend their scheduled lessons. He was already imaging the brats scrubbing cauldrons for hours on end, or better yet cleaning out the bedpans in the Hospital Wing, when he rounded the corner.

He stopped short, temporarily frozen by surprise and fury, at the sight of Potter tackling Malfoy to the ground.