"I think I've got it," Fred whispered softly enough that George almost didn't hear him over the din of the common room.

"The parchment?" George whispered back, but he didn't wait for an answer. "Here." He took Fred's hand and pulled them behind one of the chairs in the corner.

Fred pulled the parchment from his pocket, where he had taken to carrying it ever since coming to the conclusion that Messrs. Moony, Wormtail, Padfoot, and Prongs were trying to show them something. He paused for half a second, suddenly afraid that he was wrong and that the parchment really didn't do anything other than encourage people to try out passwords on it. It was a good enough prank on its own, and Fred would have admired it if it hadn't been done to him.

"Oh, come on. Show me."

Fred touched his wand to the parchment and said, as loudly as he dared in the crowded common room, "I solemnly swear I am up to no good."

Ink blossomed from the tip of his wand and spelt out the words, 'Messrs. Moony, Wormtail, Padfoot, and Prongs proudly present the Marauder's Map'.

"So that's what they were for," George said. "I was starting to think that someone was trying to take the mickey out of us. But a map of Hogwarts, that's worth a password." He leaned closer to the map, taking in a number of corridors he had not known existed. "I think this even has the secret passageways on it."

"Better than that," Fred said. "Look!" He pointed to a small dot that was moving down one of the third floor corridors. "Argus Filch," he read, "You don't suppose-"

"There's one way to find out." George scanned the map, quickly fixing on Gryffindor tower. The common room was a mass of dots, each labeled with a name, dancing around each other as Gryffindor celebrated their first win of the Quidditch season. "See, here we are, in this corner. And Bill and Charlie are over by the fire, talking to Livia Cohen and Keith Brown."

Fred looked up and quickly checked the room for Bill and Charlie. "That they are. Now, Livia's left, she's going back over to the table with the food."

"Yes, she is." George smiled down at the parchment- map. "This is brilliant. We can use it to avoid Filch, track people down... I think some of these secret passageways lead off the grounds. Do you think any of them will get us into Hogsmeade? That way we wouldn't have to rely on Charlie to get us Zonko's stuff."

"Better than that." Fred grinned wickedly at the third year boy's dorm. "Didn't Percy say he wanted to study for his transfiguration exam away from all us noisy hellions."

"Yeah, why?"

Fred pointed. Percy's dot was up in the dormitory where it was supposed to be, but right next to it, almost touching was another dot marked Peter Pettigrew. "So that doesn't really look like studying, does it?"

It really didn't, but George was willing to give Percy the benefit of the doubt. "Maybe they're sharing a desk."

"We don't have desks in our dorms." Which had turned out to be a bit of a problem, as Fred and George found themselves constantly needing to shuffle sensitive documents out of sight when they were working in the common room.

"Maybe Percy borrowed one from an empty classroom." A brilliant idea, even if not the sort of thing George could really picture Percy doing. "We could probably manage it now that we've got this map. All we'd have to do is get up at three in the morning and avoid Filch."

"I really don't see Perce as the type to steal a desk," Fred said. "I think he's snuck off to have some private time with Mr. Pettigrew. Speaking of which, I don't believe we've met the fellow."

"There's an Agatha Pettigrew in our year," George said thoughtfully. "She's a Hufflepuff, if I remember rightly."

"Probably Percy's Pettigrew's younger sister," Fred said. "Probably Percy's Pettigrew's, that's a bit of a mouthful. We need to think of something better to call him."

"Percy's boyfriend," George suggested. "Since that's what you think he is."

"Percy's boyfriend," Fred repeated. "You know, I reckon we should share this new development with Bill and Charlie. They ought to know that one of their little brothers has moved on from Hogsmeade dates to snogging in the dorms."

"They'll want to know how we found out," George said. "And Bill will probably get after us for spying on Percy."

"We don't have to tell him about the map," Fred said. "In fact, I vote we don't. Head Boy Bill might not approve of us using it to get up to mischief. Might even confiscate it and use it to make sure we don't go sneaking out after hours."

"He'd get after us worse if we didn't tell him about the map," George said. "Think about it, Fred. Seeing him on the map was just innocent fooling around. If we claim to have walked in on him, then we have to come up for a reason to be in his dorm."

Fred snorted. "Like we need a reason to pay a visit to our beloved, highly esteemed-"

"The last time we went in his room we hid dungbombs under his mattress."

"Point taken." Fred had to think for a minute before he came up with something else plausible. "We could say we wanted help with our charms essay, the one due Monday that we've been putting off."

"On Saturday night, while everyone except Percy, who has already told everyone that he needs to study for his transfiguration test, is in the common room celebrating our victory against Ravenclaw? Bill will see right through that one." George frowned. "The only other thing I can think to do would be to say one of his roommates told us, and if none of them know, he'll think we're making it up."

"But if we tell one of them-"

"They'll tell Bill they heard it from him and then Bill will know we're making it up," George said. "Besides, Bill is bound to find out about it eventually. And, if we tease Percy a little bit about it before he does-"

"-then Percy won't tell Bill about it."

Identical grins spread across the twin's faces.