The Weasley twins were up to mischief, as usual. Unusually, they hadn't been caught red handed in several months. If Albus hadn't been so certain of his own magical prowess, he'd have said that they'd been countering his charms and wards
As it was, he suspected that would be impossible for two thirteen year old boys, even ones as ingenious as the Weasley tended to be.
Which meant they'd found a way around Hogwarts that not even he was able to track.
There'd only been one other group of mischief makers that had managed to avoid detection so thoroughly; James Potter, Sirius Black, Peter Pettigrew, and Remus Lupin. Albus took a moment to mourn what had happened to those four boys' friendship, torn apart as it had been by war. Then he shook himself, and focused upon task.
The so called 'Marauders' must have left something behind for whichever budding mischief maker would be lucky enough to get their hands on it. It was the only explanation.
What could it be?
Albus strolled down the corridor clad in his own form of invisibility. He was patrolling the floor that gave access to the Gryffindor Common Room, partly out of nostalgia, and partly optimistic that this time he might just catch them out.
A rustle of parchment had him turning back the way he'd came. Perhaps he was in luck.
"Merlin's beard, is that Dumbledore?" someone whispered.
"Shush!" another replied. "Merlin's saggy underpants, it is!"
Albus raised his brows, hidden though they were. He'd not shed his invisibility charm – they should not have been able to detect him.
"Bugger!" one of the boys whispered.
There was another rustle, and by the time Albus rounded the corner the boys were gone, no evidence of their trail.
He smiled to himself. He always had enjoyed a good puzzle.