Head canons

You're Who

   After prodding around the castle and even adding to the Map, Fred and George knew the Marauders almost as it they were part of them. One day at an order meeting, they were talking with Professor Lupin and Sirius Black.
   "You-know-who was back at Hogwarts." Remus said.
   "They do nothing, but when I try to warn Harry..." Sirius said with an eye roll.
   "How'd you get..." George said.
   "Into the castle?" Fred finished.
   "Well, I used to have a map." Sirius said.
   "Used to, I bet I've seen it more recently than you have." Remus said.
   "I doubt it, Moony."
   "Moony?" The twins said in unison.
   "Oh... um... I didn't say Moony. I said... Loony. Like, should be in the loony bin." Sirius said.
   "We solemnly swear" George started.
   "That we're up to no good." Fred finished.
   "Where did you find it?" Sirius asked. "Peter dropped it when we switched all the parchment with the insult parchment."
   "We nicked it from Flich." The twins said.
   "How many detentions did you avoid with it?" Remus asked.
   "At least a hundred." Fred said.
   "You?" George asked.
   "Too many to count." Sirius said. "Worst thing you ever did with it?"
   "Sneaking into the Slythren doom..." Fred.
   "And switching out all the shampoo with itching powder." George.
   "The school almost got closed because of lice." Fred.
   "What about you?" George.
   "We spent months on it actually." Remus said.
   "Yeah. We repainted all the pictures in the castle." Sirius said.
   "Remember when Prongs wanted to make them say..." Remus whispered something to Sirius.
   "Yeah. But you made him change it." Sirius said.
   "Anyway," Remus was addressing the twins again. "We repainted them as best we could and charmed them to only sing 'Snape, Snape, Snivellus Snape' wherever he went."
   They were all laughing when Molly Weasley ran in. Hogwarts was under attack and Harry was sneaking people into the castle. They had to leave immendently.