Sirius couldn't sleep, and he was not the type who was content to lay in bed and think. He was bored and wanted an adventure. He rolled onto his side and whispered "Oi, James!" rather loudly to his friend in the next bed. James responded by turning away and pulling a pillow over his head. Beyond him, Sirius saw Peter sleeping deeply and heard his snores even from this distance; Sirius didn't even bother trying to wake him up. So he flipped onto his other side to wake up Remus, who he knew was less likely to tolerate him but it was worth a try anyway. He was about to whisper the most obnoxious "Mooooney!" he could manage, but he noticed Lupin's bed was empty. Sirius got out of bed and trotted down the stairs into the common room, where he found Lupin, still in his robes, curled up into the corner of a sofa with a book, bobbing his head to a raido playing quietly on the coffee table.
"Hiii Mooney" said Sirius, jumping over the back of the couch and landing next to his friend, laying the side his face on Lupin's arm to see what he was reading. Nothing interesting. So he focused on the music. "But when I get home to you, I find the things that you do, they make me feel alright" sang the men on the radio. Sirius closed his eyes and kept listening through several songs, very much enjoying himself. "Who is this?" he asked.
"The Beatles" responded Lupin, still fairly absorbed in his book.
"Hm, never heard of 'em."
"You wouldn't have, they're a muggle group."
"Well, they're quite good."
"The best muggle band of all time. Broke up a few years ago."
Not wanting to disturb Remus' reading more than he already had, Sirius got back up and went back into the dorm room. He found James' invisibility cloak under the bed and ran back downstairs. "Running to the library," he told Lupin, "be right back!" Lupin raised an eyebrow at the thought of Sirius sneaking off for a book, but gave him a wave as he threw the invisibility cloak over himself and hopped through the portrait hole.
Sirius came back a half-hour later with a big hardcover book under his arm. Remus was still absorbed in his book, but looked over at what Sirius was reading and laughed out loud when he saw a picture of four smartly dressed men with bowl cuts and instruments. "You like them that much?" he asked amusedly.
"I never knew muggle music was this good!" Sirius enthused. Every time a new song came on, he'd look it up to see who wrote it, who was playing what instrument, when it was written. Paul, John, George, and Ringo: The cute one, the smart one, the quiet one, and the funny one. He read about each of their lives and the nature of their work until he fell asleep on Remus' shoulder to "Happiness is a Warm Gun." Remus looked to him and smiled, letting him sleep until Remus finished his book and brought him up to bed.
For the next week, Sirius was always playing Beatles records in the common room, sending for them by owl if he couldn't find them in the library. His friends and most of Gryffindor got pretty hooked as well, to the point where when Sirius got up on a table and started lip-synching to "Please Please Me" the whole common room joined in singing and dancing. By the end of the month, the Marauders were familiar with all their hits, and Sirius could recite the lyrics to any song, or the track list to any album you asked of him. Beatlemania had hit Hogwarts.
As the Marauders stepped into Dumbledore's office, they were pleasantly surprised to hear Maxwell's Silver Hammer playing on an ornate record player and Dumbledore singing along to it softly as he finished writing on a piece of parchment with a flourish. "Now," he said, looking up to the Marauders "I suppose you all are wondering why I asked you to come and visit me today." Actually, they weren't. By this time, they were used to "visits" with school administrators, and when they'd gotten an owl from Dumbledore that morning asking them to come up to his office that evening, they just assumed one of their various pranks had been uncovered and they were to be assigned detention. But none of them said this, they just stood in a line and waited for the headmaster to continue.
"It hasn't been announced to the school yet, but we are having a dance in a couple of months. And I have been made aware of the latest trend as far as music, these Beatles." He paused and smiled. "And I was wondering if you wanted to help bring The Beatles to the dance."
"Sir?" asked Remus, raising his hand. Dumbledore smiled once more and pointed to him, indicating that he should answer. "The Beatles broke up. And they're muggles! How are we supposed to get them to the dance?" Dumbledore simply smiled at the boys for a moment before unveiling his plan.
The students had filed into the Great Hall, all in their finest dress robes, and were chatting over the soft music that was playing, waiting for Dumbledore to get up and officially start the dance. When he did, the student body fell silent. After his opening remarks, he gestured his hand up, and the students gasped to see a stage rising up on the other end of the hall, spotlights on closed curtains. The curtains pulled open to reveal four young men in smart-looking suits, but not the Beatles. It was Sirius, Remus, James, and Peter. They started playing, and from the drum set, Wormtail started singing. "What would you do if I sang out of tune, would you stand up and walk out on me?..." and the crowd went absolutely nuts. After the song was done, they didn't even pause for bows before James took the mic and started singing "Close your eyes and I'll kiss you, tomorrow I'll miss you!" Girls were screaming and dancing, and boys were singing along. When James was done, he took a bow and Sirius sauntered up to the mic, looking dramatically through his long black hair out at the audience before yelling "Why don't we do it in the road?" At this point, the men of the audience completely lost hope of keeping the attention of their dates, every girl's eyes and mind were fixed on the sexiness oozing out of Sirius Black as he belted out the rest of the song. And they went crazy when he was done. But Sirius didn't take too long soaking up the praise before backing up and ushering his friend Remus Lupin up to the mic. He started plucking out the beautiful, instantly recognizable riff on his guitar, and leaned up and sung softly "Something in the way she moves attracts me like no other lover…" Couples were dancing slowly, hypnotized by the beauty of the song and Lupin's presentation. When he finished the song, there was a moment of silence as the beauty finished settling in, and then the crowd went wild, clapping and screaming as James, Remus, and Sirius ran into each others arms, hugging and jumping in the ecstasy of performance, and Wormtail banged wildly on the drum set in his joy. The curtains closed, and recorded music started playing. And the dance went on, but the Marauders had defiantly been the highlight of the night.