This isn’t the first time that someone has royally screwed up the timelines. Actually, it happens a bit more than you might think, often on small scales and then the occasional blunder that has whole groups hopping inbetween the generations for a period of time. The ministry -- being in charge of a society that is more or less completely chaotic -- has gotten rather good at covering these issues up. No one at the ministry would tell you this head on, but the majority of the work at the wizarding government is centered around cleaning up everyone else’s catastrophes.
(No one said that politics were glamorous.)
But this time (oh, this time), someone really messed up. They messed up so fantastically that not even the ministry knew how to get things back to normal. It was an accident... no one could deliberately cause this much chaos. Somewhere in the Department of Mysteries, muggleborn Unspeakable Davis Walsh was combining his two loves, science and magic, in an attempt to prove the existence of multiple dimensions. No one had ever tried to combine the powers of the muggle world with the magical one, but he was determined to be the first and to make a meaningful discovery in the process.
And then there was the explosion.
His experiments imploded, sending him flying back into the restored cabinet full of time-turners, which scattered into the fray, breaking and repairing themselves over and over again.
People came running from the far ends of the department. The glass was pulled from Davis’s arm and the time-turners were halted in their endless cycle of falling and fixing. When everything was cleared away, no one felt strange and so it was left as a minor interdepartmental issue -- no harm, no foul, so everyone went home.
The next day, strange faces began to pop up around the wizarding world. At first, they were familiar, albeit somewhat unnerving. Babies and toddlers were quickly being replaced by their twenty something year old selves. It was somewhat uncomfortable, but after the idea of it sunk in, the majority of the wizarding world found it to be quite fascinating to see their children in the future.
It wasn’t until a week or so later that things started to get strange. The ministry had been attempting to round everyone up, to inform their families of their existence, and to send them to their closest kin until the problem had been sorted out. Databases were established, family lists were created, and it seemed like the ministry had found a way to create order in the middle of the madness once again. So when they came across a girl with dark, curly hair, she was placed in line with everyone else.
“Name?” the ministry officiant asked in a dull voice as the girl stepped up to be accounted for. She blinked, but seemed to remember herself before clearing her throat somewhat awkwardly.
“Lily Potter.” she said in a clear voice. The officiant began to flip through his pages, settling on the surnames beginning with ‘P’, and furrowed his brow in confusion.
“Lily Potter is accounted for,” he said roughly. “Birth year?”
“2006.” At this response, the officiant looked up and eyed her suspiciously.
“Not possible,” he said, standing from his seat in case something needed to be done about this impostor.
“Well, that’s what it is.” she said back in a firm voice, obviously getting defensive. The officiant narrowed his eyes at her and inspected her face briefly.
“Who are your parents?” he asked slowly, and the girl brightened somewhat.
“Harry and Hermione Potter,”
As it turned out, Davis Walsh’s theory about alternate dimensions proved true. He had broken into one, dragging the children of one timeline into the past with the children of another. He had mixed an alternate universe with the current one, resulting in the children of people who hated one another, who had never met, who would never in a million years consider the other attractive to be running wild in wizarding London.
Of course, the children of the two dimensions quickly came to the conclusion that, stuck in this one dimension, only one set of them could survive. Ultimately, if their parents did not end up together, they would cease to exist.
Now the wizarding world is in chaos, as the children of each dimension try everything in their power to create the reality they know and to keep from disappearing altogether. And those from the present? Well, they’re just wishing that everything would go back to the way it was.