Begins Pre-Hogwarts.
Ending, unknown.

Alterations to Canon:
None except for pre-Hogwarts events within the story.

Mostly a Gen-Fic, due to ages.
Later, Harry with one of his fellow lab rats would make the most sense.

Harry is seven years old when he is bullied severely one afternoon during lunch at his school in Little Whinging. After Dudley dumps a bunch of mud and rubbish on Harry's head his gang of fellow brutes declare loudly that they are going to help him clean up and produce scissors and, while holding him down, cut his hair at random creating a horrible mess.

A mortified Harry is further traumatised when he returns to the classroom where he receives an angry tirade from the teacher for being messy and muddy while all the other children in the class laugh at him. Unable to bare it he flees the classroom and runs out into the hallway, not even looking where he is going, unable to see for the tears in his eyes. Because of this he runs head first into the school principal.

Ordinarily Mr. Goodwine would be the first to viciously chew-out any unkempt wastrel who so clumsily dirtied one of his fine suits but before he can do so he witnesses the extraordinary. Harry's hair regrows completely right before the man's eyes, making him realise that he may have just found something valuable. He takes Harry outside, calming and reassuring him, soothing the young boy and when Harry has stopped crying he tells Harry not to worry, because his hair has all grown back.

Harry begins to panic, knowing he has done something 'freakish' in front of someone, certain that he will be punished. Goodwine reassures him otherwise, he is very pleased that Harry is special and coaxes Harry into explaining that his hair has regrown before and that his Aunt and Uncle were very angry, because it was 'unnatural'. The principal assures Harry that he'll make sure everything is okay and tells him to wait on the playground while he goes and makes some phone calls, to clear everything up.

Relieved, Harry obeys. Unfortunately for him Mr. Goodwine is not even remotely a good person. Before becoming the principal of the small, local and inconsequential public school Mr. Goodwine was the headmaster of a prestigious private school in London, a position he had obtained through blackmail and bribery. His dismissal from his position, was actually the result of him predating on young women on scholarships to the school, threatening them with demerits, bad grades and losing their scholarships if they didn't provide sexual favours. After several girls got together and reported him to the staff the school's board, leery of the scandal that would result if the media got hold of the story, paid the girl's families off and with the threat of blackmail and bribery still hanging over them from Goodwine they arranged for him to quietly retire.

Looking to restore his social standing he'd 'graciously volunteered' to take the much less well paying position as the principal of this public school, to bring his skills and knowledge to bear to raise the standards of the education provided to children from less fortunate backgrounds - and then leverage that to gain influence and kind of treatment from the community that he is accustomed to, all while he hunted for blackmail and began seeking those open to bribes and favours.

As an opportunist he sees the potential value Harry's strange quirk represents and calls an old friend from university. While Goodwine's original plan to become a doctor never worked out for him, having far too much appreciation for drinking and call girls, his colleague Dr. Ernest Haider became a successful and wealthy biotech entrepreneur and specialises in genetic engineering. When Dr. Haider hears what Goodwine has witnessed he is very interested, this is, after all, not the first such case of children with strange abilities that has been brought to his attention and he expresses his interest in 'acquiring' this child for his research.

Learning that Harry is from an abusive and potentially neglectful home is music to Dr. Haider's ears. It would only be too easy to imagine that such a child might run away from such a home and never be seen again. Goodwine assures Harry that he's spoken to his aunt and uncle and Harry can stay with Mr. Goodwine tonight and that tomorrow a good friend of his, a doctor, will be coming to see him and check to make sure everything is okay. If his aunt and uncle don't want him back then, he assures Harry, there are many people, even his doctor friend who would be happy to have Harry stay with him.

Harry is wary, and always is about anything that seems good or safe, but is too tempted to refuse. The very next day he is being driven past a security gate and down into an underground parking garage of a lab building and complex owned by Haider. He has no idea that he is about to become a willing guinea pig for Haider's investigations and experiments. Given a nice, clean, spacious room with new clothes, a few toys and a television all to himself, Harry decides that he's only too pleased to stay. Sure, he may be subjected to regular testing, blood draws and scans but it was still nothing compared to beatings, constant hunger and being stuffed in a tiny cupboard.

Soon Haider is convinced that Harry is like the others subjects he has acquired. Harry subsequently meets two other children in residence at this facility, children who are like him. Sally-Anne Perks, whose single mother died in a home invasion, at least according to the man dressed as a police officer, who was actually working for Haider. Whisked away she never learned the man who spoke to her was the one who murdered her mother and would subsequently burn down their house with her mother's body and a substitute corpse, passed off as Sally herself. Similarly Katie Bell only has a fuzzy memory of the car accident that killed her parents and her brother who died on impact. Her memory is actually only fuzzy thanks to a drug designed by Haider to create retrograde amnesia. In reality the car accident was staged and minor, the paramedics who promptly arrived worked for Haider and they sedated her family before instigating a second, much deadlier collision. Katie being whisked away to be pronounced dead and relocated to Haider's lab.

A few months after his arrival another girl arrives, Hermione Granger. She has a similarly terrible story of losing her parents this time to a gas main exploding in her parent's dentistry practice. They grow up together over the next two years, becoming friends with a powerful bond to each other, sharing similar suffering and having their unique and strange abilities in common, they call themselves the 'Lab Rats'. In this time, under intense pressure and rigorous training they each gain the ability to do some magic at will.

All of them, to one degree or another, can levitate things or make them fly towards or away from them. Hermione demonstrates the ability to change the colour of objects she touches, which in turn Harry and Katie replicate but much less skillfully while Sally seems to lack that skill all together. On the other hand Sally can light candles at will, as can Harry but neither Katie of Hermione can perform the trick. Harry alone seems to be able to augment his strength and alter his appearance and is the primary subject of Dr. Haider's testing because of it, intent on unlocking the secrets behind Harry's (metamorphmagus) talents.

Everything changes one day when Harry, worried about something concerning the girls, pulls a piece of information from the mind of one of the doctors doing a test on him. He is subsequently subjected to the classic tests for psychic potential, including trying to perceive the shapes drawn on cards being held up to him by reading the mind of the test-giver. The man administering the test is none other than the man who murdered Sally-Anne's mother and Hermione's parents and Harry sees it in his mind.

Harry's crude and panic-exacerbated legilimency puts the man in a coma and his shock keeps him from blurting out the truth to any of the other doctors or staff. Finding some privacy later he tells Sally and Hermione, along with Katie, what he saw. They don't want to believe him but the more they think about it the more sense it makes. How did Dr. Haider learn about the girls' abilities? He shouldn't have known they existed until the 'accidents' and then after that, how did he discover they had their abilities? He just showed up and took them away.

The lab stops conducting psychic aptitude tests on Harry after the coma inflicted on one of their own, instead trying to get him to control animals or testing him with MRIs. Harry and the girls practice on each other, determined to learn the skill so they can look into the minds of their captors to see the truth and get to the bottom of things. Several months is practice enough and the Lab Rats use their abilities to slip out of their room, getting to Haider's office and restrain him and dig into his mind. There they see the truth of his operation and their combined anger causes them to effectively turn Haider into a vegetable.The discovery of his insensate body the next morning incites suspicion and fear among the others working at the lab who, correctly, suspect it is the doing of the Lab Rats. They discuss contingencies and one of the girls sees that contingency in the mind of one of the workers and the Lab Rats plot their escape. A battle erupts with orderlies armed with restraints, prods and drugs attack them and they combine their skills (which they have been building in secret) to counter-attack. In the aftermath they flee the building together and leave it on fire after they cause a generator to explode.

The live on the streets after that, holing up in abandoned buildings, helping themselves to people's wallets and shoplifting by using their growing variety of skills until the day that Harry, Hermione and Sally's Hogwarts letters arrive. Katie never received her letter because the owl meant to deliver it couldn't get to her in the lab and eventually returned with the letter unopened, which was never followed up with because that falls (ordinarily, not like in Harry's case in canon) to the board of governors who don't care if a muggleborn fails to reply.

The Rats at Hogwarts:
From here you could go almost any which way you want. Clearly the other Rats will want Katie to go with them to Hogwarts and will need to persuade someone in authority to reinstate her to Hogwarts' student roles. Harry's letter in canon gave no directions to Diagon Alley but then he was born of magical parents, perhaps directions and other orientation material is included in the letters to muggleborns.

At Hogwarts are they all sorted into the same house or split up? Do they show off their pre-existing wandless skills or, having learned the value of concealing their strength, do they hold back? They have grown to adopt a mentality of distrust, self-reliance and borderline paranoia concerning adult authority figures and have already taken lives at the lab during their escape - perhaps even criminals while living on the streets. How will they fit in with the other students and whose suspicion will they arouse?