Troublesome Tommy's Small Solution
George Weasley appeared behind him with a crack. "Gah!" said Harry, spinning around, wand in hand. "Don't do that to me!"
"What?" George said, looking wounded. "I would never do something like—"
"This," continued Fred, appearing on Harry's other side.
"No, seriously, guys, quit that," Harry asserted. "You never know what I might do next time."
"Fine, fine," George said. "We'll try to appear in front of you, then." Harry nodded, and the conversation moved on.
"Aah!" Harry jumped, sending the Shrinking Solution he was working on flying over his shoulder.
"Sorry about that," he sighed, getting out the cleaning supplies and ingredients for the antidote. "But really, I did warn you that—whoah!"
Turning around, Harry saw not the miniature baby Weasley he was expecting, but a pale, black-haired baby with a strangely flat nose in a pile of black robes. He couldn't see what colour the baby's eyes were, as its face was currently screwed up in frustration. He was willing to bet, though, that they would be either the red of Voldemort or the chill darkness of a young Tom Riddle.
Thinking quickly, he stuffed his cleaning rag in the mouth that was opening for a wail, and conjured some ropes to bind the baby. He then deposited it in an empty storage cupboard, and performed a strong locking charm on the door.
'Well,' he thought, 'at least this gives us time to find those last two Horcruxes.' He headed towards the main area of the safehouse.
"Erm, Hermione? D'you know how long Shrinking Solution lasts, without the antidote? Only, there's something I think you ought to know..."