One year after Sirius Black's death at the Battle of the Ministry (the first true battle of the Second War), it was over. Voldemort had fallen at Harry Potter's hands, as prophesised, and the Light prevailed.
(Harry's right hand was shattered and his face was shredded and bleeding. He didn't even cast a Killing Curse; he'd just rushed up to Voldemort and stabbed him with Gryffindor's sword as curses flew around him. Voldemort's eyes changed from red to blue before he died. Harry didn't know what that meant. He just knew he wasn't going to get the image out of his head for a long time.)
The Wizarding World had all but lost hope after Harry Potter's disappearance the week after Voldemort was discovered to have returned. The rumors were rampant; he'd fled to the safety of a foreign country, he'd gone to Voldemort's side, he'd been killed or kidnapped by Deatheaters... no one guessed that he'd been hidden in the dungeons beneath Hogwarts to be trained into the weapon they needed.
(He cried every night at the beginning of his training. He was tired and in pain and missing Sirius. They drilled him in combat, strategy, magic, leadership... anything to hone him into the assassin and general they needed. He was 16. Towards the middle, he became numb. He would run for hours without stopping at his instructor's direction, ducking charms and hexes and curses without breaking stride. He could shake off Imperius like it was a tickling charm. He could run on a broken ankle. He would sacrifice soldiers calmly on a theoretical battle field because he just didn't feel anymore. At the end he flipped back to himself again. He talked back, refused to sacrifice innocents, cracked jokes. He cried again, but he got up stronger. He was nothing if not adaptable.)
As Voldemort reigned terror on the United Kingdom, conducting raids on wizards and muggles alike, fear grew. The muggle world was told that a mad extremist was bombing various locations, and that the government was doing everything it could to stop him. Thousands died, then tens of thousands, as Harry Potter was pushed beyond his limits in a windowless series of dungeons, released only for three battles; The Battle for St Mungo's, The Battle of Diagon Alley, and the week long, horror-filled Siege of Hogwarts. The first two were counted as training exercises by his instructors, despite the fact that people were dying around him. They covered his face and his eyes to stop him being recognised and set him loose in the field, encouraging him to kill and becoming for and more frustrated as he chose to disarm and disable. Ron and Hermione sometimes trained with him, though they also continued to attend school, and they would sneak out to fight alongside him at the Battles.
(The three of them caused an international incident when a muggle news camera picked up the 'Special Task Force Soldiers', as the muggle world believed the black swathed Aurors to be, taking orders from a child wearing a soldier's uniform, two other's in school dress nursing injuries and weapons. Britain was called into question at the UN for using child soldiers. The world began to believe rumours that the UK had been training children to be assassins from birth. The Minister called Ron and Hermione into his office to rail at them, but Hermione pointed out that that was exactly what they were doing to Harry and continued to scream at him for nearly an hour. Ron thought it was hilarious.)
As celebration rang out over the UK, Harry was rushed to hospital. He was in St Mungo's for a month, hidden away at Grimmauld Place for five, flown out of the country after six. The world praised his name but feared him in the same breath. He couldn't walk down the street without being mobbed or at least stared at. He was tired, traumatised, and 17. He needed to escape, and that's just what he did.
(Ron and Hermione wanted to stay, and he got that. It didn't mean he didn't hold onto them for a very long time at Heathrow Airport, tears tracking down his face.)
The Wizarding World continued to talk about him with reverent voices, like they did with Dumbledore and Merlin. They said he'd disappeared to train more to come back and rule them, that he was living on an exotic island somewhere, that he'd bled out on the battlefield. No one thought to look for him in a normal house in small town Ohio in the United States of America, two states away from the nearest Magical Community, in a country where the name Harry Potter meant no more than a European curiosity.