The young man ran his fingers through his short, frizzy brown hair, trying uselessly to straighten it. Of course, if all went well, no one would see him or his messy hair beneath his godfather's invisibility cloak.
He adjusted the Time Turner around his neck and looked at his wristwatch. He turned a dial on it and peered around carefully.
Only one thing changed: ahead of him, closer to the crowd of passing Muggles, a shadowy shape appeared. The boy nodded to himself. Just like Mom said.
The shape glanced from side to side, and the boy's eyes widened. That's me, he thought. Me from the other timeline. But... why am I a ginger?
As a very large man appeared, nearly twice as a tall as anyone there, the boy followed his other-self forward. Something had happened here, something to split reality into two timelines, and it was his job to resolve it. Since, apparently, his other-self had caused the split to begin with, the boy felt a certain satisfaction at correcting it himself.
He heard Hagrid explaining how to get to Hogwarts, leaving out the crucial detail of to get onto Platform Nine and Three-Quarters, just like in the stories Harry Potter liked to tell. And here, the time traveler's other-self did something very simple. He laughed out loud.
Suddenly, using his watch to see both timelines, he could see two Hagrids. One kept saying goodbye. The other heard the laugh and became self-conscious. He said, "Am I forgetting anythin'? Oh, righ', yer leaving from Platform Nine and Three-Quarters."
The boy didn't have time to catch the rest of the conversation: Harry's train would leave in moments. He had to focus on making both Hagrids act the same, so that the two timelines would be reunited. He twiddled the dial until the right Hagrid seemed more solid than the other, whipped off the invisibility cloak, and ran towards Harry and Hagrid. Before he could skid to a stop, he ran full-force into the half-giant's leg and fell over.
"Yeh all righ' there?" asked the large man, bending over in conclusion and offering him a hand.
"I think so," said the boy, standing up and hiding the invisibility cloak behind him carefully. An idea struck him, and he laughed at himself. "I should know better than to run into something solid! That's never a good idea."
A smile twitched under Hagrid's beard as he walked away. Hagrid turned back to Harry. "I almos' forgot. Yeh've got to run into the solid barrier between platforms nine and ten at King's Cross-it's a wizards-only platform, see."
The boy time-traveler smiled and fiddled with the dial on his watch again. There were no shadowy shapes, no splitting in timelines. Whatever changes were made here, they were now permanent. No more alternate reality.
Mother would be pleased.