Disclaimer: I don't own 'em!

Summary: Harry discovers that there's a silver lining in every cloud, but why does he keep getting sick?

Growing Pains, by Shedoc

Each step away from the little crowd on the platform hollowed Harry out. His uncle's fuming silence, his aunt's manifest disapproval, his cousin's outright loathing closed in around Harry like a living, breathing cloud, and it was Harry could do to put one foot in front of the other. He wanted to balk, to turn and run, to fling himself at the one person he felt safe with, and beg to stay with his safe harbour. He couldn't though, he didn't deserve to. He didn't deserve the protection of the one he trusted, especially after he'd led them straight into danger, straight into pain and fear.

They didn't return to Little Whinging straight away. Apparently, Smeltings had a policy that the students in their final two years of school were to use personalised stationery, available only from a particular store in London. His aunt and uncle were taking Dudley to order his stationery for the next two years, and Harry was to come with them, as he wasn't to be trusted in the car.

"May I let Hedwig out?" he asked as his uncle switched the engine off, "She could fly to Privet Drive, and that way no one would see her in your car."

"Very well," Aunt Petunia said through stiff lips and Harry undid the cage quickly. Hedwig hopped silently onto his wrist and he smiled at her, sliding out of the car and walking to the edge of the parking building while stroking her feathers. She nibbled his fingers anxiously and he shushed her gently.

"Wait in a tree in the back, Hedwig, I'll let you in the moment I get there," he whispered, "Safe flight."

She hooted and launched herself obediently, arrowing away into the bright sky. Harry turned and fell in behind the Dursley's, walking silently close enough not to lose them, but not close enough to 'intrude'. He stopped outside the door of the shop they were about to enter and moved to the edge of the footpath, prepared to wait outside for them. His uncle gave him a sneer of approval and Harry stuck his hands in his pockets, his fingers brushing his wand for a moment. It was hot and airless on the street, as though there were too many people breathing the same air. Shoppers and tourists thronged along, well dressed and pleased with themselves. Harry watched them all, evaluating them for possible threats. One little old lady dropped her bag in front of him and he grinned, picking it up and offering it to her politely.

"Wotcher Tonks," he muttered, "Stuck watching me already?"

"Thanks ducky," Tonks replied sourly and walked on a little way. He deliberately looked away from her, so as not to draw attention to her.

By the time the Dursley's emerged, Harry's shirt was sticking to him and he felt decidedly unwell. Dudley was smirking at him in a very satisfied manner, which meant he'd just got a present and Harry had not. Harry was used to that and it no longer bothered him. His aunt peered at him and then shoved the bags she was carrying into his hands.

"Carry these and don't complain and you can have one of the free samples they gave us," she snapped and Harry trailed along behind obediently, not at all interested in the bribe, though he was aware that she had spoken at a higher volume than she normally did. They must have suspected that they were under surveillance and this was their version of treating Harry well.

He spent the ride to Privet Drive staring blankly out the window. Dudley was whining about a new game he wanted, and trying to get an increase in his spending money yet again. Vernon was complaining about the new accountant in his department, and Petunia was griping about the next door but one neighbour who was having an affair while her husband was away. By the time the car pulled into the Dursley's driveway, Harry was longing for the silence of his spot by the lake at Hogwarts. He lifted Hedwig's empty cage and his trunk from the car, carrying them up to his room and opening the window to allow his owl in. He filled her water container and put out food and owl treats for her before toeing off his shoes and sitting on his narrow bed.

"Here," Aunt Petunia threw a book onto the floor, bound in dark blue leather, "This is the free sample we were given. Ugly thing."

"Thank you Aunt Petunia," Harry said tonelessly and got up to put the book on his desk. From what he could remember of Muggle stationery it was A4 sized and had been divided into five sections by a thick textured blue cardboard. The pages were lined faintly in blue and the paper was high quality. Harry returned to his bed and sat down, drawing his knees up to his chest and wrapping his arms around them.

In his mind he wasn't in the small room that his relatives had grudgingly allowed him, he was back in the Department of Mysteries, watching Sirius fall through the veil, orphaning him once more. Harry forced his mind to review the year, and step-by-step he recognised his mistakes, making himself a solemn promise that he would do better the coming school year.

Mistakes acknowledged; Harry turned his mind to the prophecy. The prospect of becoming a murderer filled him with dread, though the thought that he would be leaving the world to Voldemort's rule upon his death was no better. The problem was that Harry had no idea of how to kill the vastly powerful wizard. Just the memory of his one experience with casting an Unforgivable curse made him feel physically ill, and indescribably dirty. No matter what he'd been feeling at the time, the attempt to cast the Cruciatus Cruse on Lestrange had been a huge error, and one that he'd never be able to repeat. If he sank to their level in ridding the world of their poison, he was no better than the Death Eaters and their Lord.

Dumbledore expected him to fight on the side of the Light, against the Darkness. Dark and Light had fought against each other for time immemorial, and Harry knew it was an overused cliché, but neither one could exist without the other. No matter how brightly Light shone, eventually it would dim enough to allow the Dark to creep back in. Dark had its ways and its tools, and Harry knew that there was no excuse to start using the Darks own tools against it. Light couldn't win that way, and shouldn't try.

That meant he had to find another way to defeat Voldemort. Another series of spells or tools had to exist somewhere that Harry could use without lowering himself to Voldemort's levels. He banged his head on his knees, and wondered why he hadn't given up Divination with Hermione and taken Arithmancy instead. He'd give anything to know more about the structure of spells and the way they combined with the casters magic to produce the results desired.

Harry leapt from his bed and stumbled to his trunk on shaking legs. He yanked out parchment, ink and quill, using the top of his trunk as a table to write on. He'd send a letter to the Professor of Arithmancy and ask if he could be included in the OWL level classes. He'd study with the fourth years if they'd let him, anything to learn more about the way the spells worked. Hedwig fluttered to his side and he fastened the letter with shaking fingers, giving her directions in a soft voice.

Harry pulled himself up, wondering why he was so shaken. He'd just been sitting on his bed … Harry frowned and headed downstairs to the living area. His aunt was wearing different clothes and Dudley was playing the game he'd been whining for.

"Finally decided to join us?" his Aunt snapped, "You've been sitting like a statue for three days!"

The reply to his request was a favourable one, and Harry was allowed to study Arithmancy, provided he could pass the third year exams upon his return to Hogwarts. As a mark of confidence, the teacher sent Harry a copy of the third and fourth year books from Flourish and Blotts, and Harry started studying hard.

He decided that he'd use the free gift the Dursley's had given him to record his studies in, and used the sections of the book to keep his studies separate. They hadn't been given any homework this year, because the teachers didn't know what their OWL results would be and therefore had no idea what subjects they'd be taking. The first section of the book Harry used to take notes on Arithmancy in general. Though he was in the habit of writing on the books he owned - scribbled notes dotted the margins of all his schoolbooks - Harry had soon discovered that his notes would need to be a lot more detailed than in previous years. He'd also decided to go back to first year and pull apart each spell they'd learned, mapping out the Arithmancy of each one. He'd do this for all five years of his schooling for Transfiguration, Charms, Defence Against the Dark Arts, with the final section of the book a combination Herbology and Potions, as many plants had magical properties in their own right and combining them into a potion required a deep understanding of all their interactions.

Something unusual happened that Harry would have noticed in that first month of study if he hadn't been so immersed in his work. No matter how much he wrote in each section of the free gift, he never ran out of pages. Unintentionally, Harry's magic had surged and cast an infinite spell on the book itself. He would never run out of space, and the book itself was virtually indestructible. Most Witches and Wizards had surges of accidental magic as they grew in their early years. This was one way that their parents learned that their offspring was magical and usually tied into an instinctive desire to prevent an accident or summon a toy that was out of reach. Hogwarts had wards up to prevent these unpredictable surges, as teenagers and their emotions and hormones could make for some pretty impressive chaos if their magic was unchecked. By the time the students graduated, they were better able to control their magic and the incidence of accidental magic was almost unheard of.

As usual there was exceptions to the rule, and Harry was fortunate that he was unaware that he was one of the exceptions. The other exceptions were fairly obvious if you thought about them. Pregnant Witches (and occasionally Wizards) often found that their magic ebbed and flowed in the later stages of their pregnancy, and teenage Witches were not unknown to have monthly problems initially. Then there were the particularly powerful Witches or Wizards who had to 'grow into' their powers. Harry fell into the last category. He hated being different and the scar and prophecy were enough of a difference without learning that he was also about to inherit some pretty impressive powers.

Harry had fallen into a pattern of study that would have alarmed Ron and impressed even Hermione in that first month of the holidays. He was up early, and cooked breakfast for the Dursley's, then spent the day in his room, working on the Arithmancy of the spells he knew. He would emerge when Uncle Vernon roared 'Boy!' up the stairs and eat his portion of dinner quickly before heading back upstairs to study for another few hours. As he wasn't moving around much, the small amount of food he ate was enough to sustain him, though he lost some weight, and by sitting at his desk in front of the window he got enough sunlight to stop his skin from becoming too pale. The members of the Order that were watching him had to have been pretty bored.

Remus Lupin had started writing to Harry every fourth day after Harry's first letter to Ron went unanswered. It had been a crushing blow to think that his best friend in the entire world no longer wanted anything to do with Harry, and he'd very nearly given up on the spot. Only the thought that by giving up he'd let worse things happen to Ron - who was still considered his best friend even if the other teen wanted nothing to do with Harry - stopped him from throwing the Arithmancy study away. Harry was grateful for the werewolf's letters and made sure to tell him that. He dutifully reassured the other man that he was not being mistreated and managed to refrain from asking questions about the Wizarding world - after last year he knew he wouldn't get any answers anyway and didn't want to put Lupin in the position where he had to try and answer impossible questions. He got the Daily Prophet, and read it cover to cover each night before he went to sleep. There was nothing in there to alarm him about Voldemort's movements and the Ministry was continuing to urge the Prophet's readers to constant vigilance. The phrase reminded Harry of Mad Eye Moody.

Three days before his birthday, Harry woke to a mild headache and a general sense of being unwell. The scar on his forehead wasn't hurting at all - it had in fact been oddly quiescent - so Harry shrugged the symptoms off and went about his daily routine. He had a difficult time studying in the evening as his headache had increased, and he went to bed earlier than usual in an attempt to sleep it off. He tossed and turned for most the night, and when his aunt stormed in to find out why he hadn't got up to make breakfast, he was in no condition to reply to her. His forehead was dotted with sweat and his body shook with malaise.

Harry never saw Petunia lock Hedwig in her cage, and nor did he notice her closing the bedroom door, afraid that her family would be blamed for Harry's sickness. By lunchtime his fever was dangerously high and he was too ill to move from his bed to answer even the more basic calls of nature. Nausea had kicked in by nightfall, and when two red headed Wizards popped into his room three minutes after midnight, Harry was lying in a pool of bodily waste, choking on his own vomit and slowly turning blue.