He wasn't sure how it happened, the trauma too great for the body to form memories. But when he looked back on those moments, he figured it went something like this: his body-less soul stayed in place even as his body was incarnated by his own spell. Aided by the Horcruxes, it was aware even in its incomplete death. He felt it breaking, then, his already weakened soul. It jarred him out of his daze, and to stop the breaking, he latched on the only living thing that could sustain him.
He thought long and hard how best to describe what happened on the joining. One of the analogies was a splash of colours on a white canvas. All that he was, splashed on a blank canvas of an infant soul. It could have been a disaster.
Instead it became a painting.
The most magnificent painting of his life.
He took it as an opportunity it was. He couldn't really take it any other way. His infant brain saw each day as a revelation of a new world. Good or bad, he 'learned' from each day, taking in the information offered.
He learned about the muggles most of all. About their beliefs, their values, their way of thinking, their technology.
He was a cuckoo chick in a sparrow nest. Full of dumb, simple birds, too caught up in their own survival to notice anything wrong. The same as a cuckoo, he made sure he was well taken care of.
His new family disliked him at first, fearing magic and himself. But he knew how to sooth their fear, how to endear to those who were suspicious of him, how to use others' guilt to get what he wanted, to charm and cajole his way into their hearts and minds. It was a process, a long term project, and it started bearing fruit when he was three and articulate enough for the conditioning of His family to really take effect.
It was also the time his magic started budding. It was shaky and clumsy at first, but he practiced, from little fairy lights that shone above his bed at night, to opening flower buds in his Aunt's garden and making them longer lasting, and lastly, subtle little pushes to peoples' minds, making them forgetful, forgiving or distracted. By the time he was seven, he was an accomplished puppet-master, yanking the strings of his chosen group of people. First was his new family, Petunia, Vernon and Dudley, then a squib neighbour, later two teachers at his school. Soon, the whole neighbourhood was caught in his web.
It was a warm summer morning and he was just making his rounds around his territory. He stopped at a house of a recently divorced Mrs. Connor, getting a piece of freshly made apple pie. He helped her trough her depression after her husband left her for a younger woman. He made sure to use magic to make his presence calming and uplifting, leaving on her subtle traces of magic every time she looked him in the eye.
She was useful to cultivate, an Electronics professor who loved to chatter about her chosen field. He encouraged her to be up to date with any new discoveries and technologies, and was an attentive listener to all her findings. He discovered her when he got a little game station thing Dudley liked to play. He usually didn't receive presents like that, since he made his preferences for 'useful' gifts known a long time ago. But that time he got a game, and predictably damaged it with his magic in a two days time. Annoyed, he tried to take it apart one day in the park, to see how it worked and what did he do to make it stop. Mrs. Connor approached him, then, and after discovering his high intellect, described to him why the toy broke. They fixed it that day on her front porch.
Of course, it stopped working again that same night, during his routine practise with magic in his room. After that he decided to learn some more about its workings and fix it himself. He made himself a regular visitor at the woman's house, becoming her avid pupil. It didn't take long for him to figure out what was destroying the little machine, and how to twist his magic to avoid it.
In the end, the game was pretty much useless, broken and fixed too many times to truly be whole again. But Christmas was coming and he made a wish for another game. He made sure he got it.
It was a Tamagotchi. The newest of the new, the game came well recommended, and with a push of magic Vernon bought it for him. It was egg like, with a pet that hatched to be cared for.
He could care less for the pet, but he did found interesting that muggles liked a creature that wasn't a Common animal. Tamagotchi was supposed to be an alien from space. It made sense, he surmised. Muggles craved magic and higher power, even when they feared it.
He showed his new toy to many people, from children to adults, monitoring their expressions and behaviour. He didn't quite know why, but he had a feeling that he was on a cusp of something. Something great.
He soon grew bored with his virtual pet and decided that tweaking the program would be much more interesting. He found he couldn't do much, the technology itself being the limitation he had to overcome. It changed his view on things. He always scoffed at the mere mention of the Misuse of Muggle Artefacts Office, both at the wizards who worked there, as well as the people who created such objects. Only now he found how hard it is to charm muggle objects. And how limiting.
Technology worked in linear patterns, cause and effect. It was simple and primitive, easily broken and energy inefficient. Magic, however, was complex. It relied on will and intuition, and even a simple spell could be manipulated to achieve intricate results. It was hard, to break down the magic to its most basic form, to its component parts, to change one part of the machine to make it do something else. It was time consuming and he felt like he had to dumb himself down to achieve it.
He figured it would be easier with a wand, magic more focused and refined, as his free and sometimes Ritual magic was not quite capable.
So now, he was at Mrs. Connor's, figuring out how technology worked, not to change it, but to recreate the effects with magic alone, subtle and unnoticeable by muggles.
It was slow going, but it passed the time during long holiday months with nothing much to do. Already, his Tamaghochi was almost empty, only the casing remained. He made the power source out of his own blood, crystalized under the Full Moon and immersed in his magic. Next came the runes written on the inside of the casing with Oak ash, for power. Next came a few strands of his hair, carefully knotted. Each knot contained a memory of his time playing his Tamaghochi, how it behaved, haw it looked, functioned. In the morning, at Sunrise, he turned it towards the rising sun and breathed on it, breathed into it life.
And the Tamaghochi woke up.
Harry was nine when he learned how addictive games were for people. His family visited the Arcade in London, and it was full of people, playing the games there, lost in their own world.
While Dudley rushed to the consoles, he took a look around. He talked to some of the gamers and it soon became clear that the majority of them used games as an escape from their mundane reality. They viewed their lives as oppressing and discouraging. In the games, they could be heroes, they could be winners, they could be the best. It was the only magic they could ever have.
He told this to one of the teenagers there, right before they left home. The boy was visibly upset, which quickly turned to anger. His words were sharp and cutting, hissing about the stupidity of children and minding his own business. He only looked on, amused by the reaction.
He was pulled out of the confrontation by an older man, who looked disapproving at them both.
"Games may be for fun, they may be an escape from a hard life, but they are also made for learning." Lectured the man.
"You learned the alphabet through a song or a game, didn't you? Many things can be learned through games, because while having fun the person doesn't know they are learning. If you sing a fun song enough times, you may learn the alphabet, and one day the whole class will simply know it, without realising when. Or that game there, it is a bit like driving a car, like your father, see? If you play it, you might have an easier time learning how to drive."
It was certainly food for thought.
All who knew him would be surprised by his living situation. They would be surprised that he was living with the muggles and letting them stay alive. They would be stupefied to know he was learning about their technology, their habits.
That was why he was the Dark Lord, and they were only good for being his minions or his prey.
He was perfectly aware of his situation, as well as all far reaching consequences of all his actions. He was Lord Voldemort, and now he is Harry Potter.
Trapped in an infant body, he was limited to endure the life given to him by circumstances outside his control. No Death Eater was trusted enough to help him, even if the state of the Wizarding world were stable enough for them to take him in. The war ended with his 'death', which made his the losing side. All that he fought for will be hated and destroyed, without thought of usefulness or rightness of his beliefs.
And here he was, in the body of the child from the opposing side. The Light side, as Dumbledore named it to gain followers. He was in a perfect position to start again, without the pre-existing bias that all he said was morally wrong and evil. He will have the perfect stepping stone to achieve all he ever wanted.
Power, Recognition and the Rise of the Magical World.
He will have to be patient, of course, wait for the right time, wait for the horror of war to be just a scary distant memory no one wants to think about. For the wounds to heal, the ecstasy of victory subside, for the mistakes and failings of the current Ruling body to come forth. Wait for the unrest to start again, for people expecting more from the government, crave change again after a period of wanting only peace and stability.
Ten years was a perfect amount of time for him to be gone. Then he will be called by Dumbledore himself, to his rightful place, starting Hogwarts again, building connections, exploring magics, gaining allies. Five years after that, until he could legally own a wand at fifteen.
Then it was no stopping him. No prophecy to hold him back.
Because it was correct, that day a boy did defeat Lord Voldemort. Such pity he didn't kill himself too.
Now he could rule as Harry Potter.
He was in the park again, tinkering with another game. It was one of Dudley's, long since broken. He wanted it to show his thoughts. After quite a bit of work and magic, he could make it show a simple picture made of dots in the middle of the screen, when he willed it strongly enough. It was a tiresome process that would certainly be easier with a wand.
That brought his thoughts to the Wizarding world.
The worst problem, he thought, were muggleborns. They were the link between worlds that shouldn't be connected. Barring them from the Wizarding world was one way to solve the problem, killing them was another.
But he wasn't blind. He noticed the losses suffered on both sides of the world, dead husbands and wives that will never again borne a child. Every drop of magical blood spilled was a tragedy, and while losses were unavoidable in a war, he had still wanted to end it quickly. That is why he pursued the Prophecy, wanting to destroy the hope it brought his opposition on the brink of his victory.
But maybe there was another way. A way that would bring in new wizarding blood, while preserving old knowledge and traditions. A way to teach young muggleborns the Old ways, to change them, to make them purer and make them forget all about their Mundane life.
He made an object capable of doing something similar, before. Less elegant, of course, much more obvious and destructive. Something made for war. But still, similarities were there, enough to give him a base to work from.
It was his Diary.
The Diary was a Horcrux, first and foremost, but it was not simply a soul in a book. It was a complex work of Soul magics and Mind magics, with memories and instructions embeded into it long after its creation. Contrary to all his other Horcruxes, it was made to possess, to take root in another person's magic and sustain itself on it. It was made to then use that magic and link it to the dormant Blood seal carrying the gift of Parseltongue. Using Parseltongue with the Vessel's mouth would be enough to open the Chamber of Secrets, releasing the monster, having it kill only muggleborns but still sawing enough panic and horror to substantially weaken the school. It would be the prime time to attack and Hogwarts would find itself fighting on two fronts.
Such was the plan, anyway, even if it was never implemented.
The Diary was a relic of the old times and peace needed a more subtle approach. A more 'enjoyable' approach.
So Harry will design a game. It will be an innocent game for the children to play, it will teach them basics of magic, congratulate them on Yule instead of Christmas, teach them wandless tricks that seem harmless, describe countless wondrous facts about magic and Magical world.
It will be made to change a child's way of thinking. Lord Voldemort learned that control over the children enabled control over their parents and the future generations. Dumbledore was a master of the game and a war general such as Voldemort couldn't hold a candle to a barmy old grandfather image he projected. Even as a teacher he once wanted to become, he would not have vast enough reach to truly influence enough people to make it worth his while.
But a game! A game ran itself, it was nice and fun and innocent, it was everything he could never truly be.
He simply had to find a way to make it happen.
Tom Riddle wasn't stupid. He was intelligent, resourceful, charming, patient. His Reign based on manipulation of the rich and influential. Controlling children was easy compared to that.
Especially through a Game!
And now, he got a second chance.