Harry James Potter was born on July 31st, 1990, with wild, spiky black hair, green eyes, and a pale complexion. He resembled both of his parents, of course, with his mother's eyes and his father's nose and face, but there were hints of another in him. James' grandfather Henry's twin brother Charlus had married Dorea Black, not Henry, so there was no explanation for the spiky, wild jet-black hair that the boy sported. The Potters had chocolate brown hair ever since Lady Iolanthe Peverell herself married the muggleborn cast-off son Hardwin Potter. The nurses said he was a mixed soul. A dead person can move on or become a ghost or be reincarnated or their soul can show up mixed in with another's. The nurses aren't well versed in the subject, so the Potters take the boy home, resolving to watch him but leave it be for now.
From the very beginning, he frequently woke up from nightmares of his other self's past life. His family was only able to gather that whatever the other soul was, it had been Japanese. He did odd things here and there, like bowing at people or putting his hands together before eating, and said words they didn't always recognize. Harry was a happy little boy, always smiling and laughing. He gave his parents, and the Marauders a run for their money, climbing on everything including the outside of the staircase. Even as his parents worried themselves sick over the possibility of a traitor in their midst, and Remus and Sirius got into a row about it and broke up and Remus stopped coming around, Harry was their light in such a dark situation.
Lily enjoyed putting him to bed. She tried to keep the same night time routine every night for him. She'd give him a bath and put lotion on him and then they'd curl up in his rocking chair where she would charm the ceiling for him and read him storybooks with moving pictures. She could pretend for a moment they were just a normal family, and revel in these precious little moments with her son. He wouldn't be little forever. Would she get to watch him grow up? The Prophecy was damning. Voldemort had to come for them eventually. Until then, she would rock him and gaze lovingly down at him as he relaxed into her arms as she read, sleepy tiny hands occasionally pointing and grazing over the moving animals and people in the books.
When he was teething, he got some potion for the pain and another to ease him to sleep, and nothing short of a body-bind curse got them down his mouth. And when he woke up crying half the night later, she'd call for the Potter elf, Holly, and tell her to get Harry some more potion. Harry woke up screaming a lot even if he wasn't teething; nightmares, Godric know why though. None of the Weasley boys or Neville Longbottom woke up from nightmares as often as he did. Sometimes, especially after an Order meeting or if James was called out by the Auror office for a job, she did it herself. They were living on borrowed time, after all. They would try, Merlin they would try, but they couldn't evade Voldemort forever – and someone from their circle was already giving information about their movements and plans to Voldemort.
Eventually, Voldemort did show up and when he blew the door down, all she could think of to protect Harry. The new anti-apparition wards the death eaters were using had been put up so they couldn't escape – this house was intentionally not set up to Floo so it couldn't be tracked that way, either. It didn't matter if she died so long as he survived. And in a flash of green light, she was gone, and Harry's emerald green eyes turned crimson red with a single black tomoe in each eye. The boy was silent, afraid and horrified and began to cry loudly as the house was blown up by the explosiveness of an unblockable killing curse rebounded.
Author's Note: Sorry this is so boring and telling not showing. I have no intention of writing out Harry's infancy as it has no affect on the story itself, so I just summarized it. For chapter one I will borrow from parts of another fanfic, revise it, and put it on here. Its my headcanon, to be honest, what I add.
01/08/2019 – Made a few edits. Took out my poor Japanese. Hopefully the google translate and anime watching attempt at Japanese in chapter one is at least excusable.