Remus can remember the first time he heard Sirius make The Serious Joke. It was probably about five minutes after they met at the Gryffindor table, Sirius having stalked over and almost too busy glaring at the Slytherins to bother making room for Remus, and James trying to straddle the bench backwards before almost knocking over his pumpkin juice.
“I’m James,” James says with the air of someone saying something hugely important, “and that git sulking next to you,” he jerks a thumb at Sirius, who glowers, “is Sirius. Ignore him, he won't bite unless you're covered in chocolate.”
“That was one time—” Sirius begins heatedly, then breaks off, face flushing red. “Well.” He visibly regains his composure, then continues with a smirk. “At least I wasn’t the one covered in fudge, James.”
“Do I want to know this story?” Remus asks curiously, and Sirius turns to acknowledge him for the first time.
“No.” He shakes his head decisively.
“Definitely not,” James agrees, shuddering.
“But,” Sirius considers, half a custard in his mouth, “we could tell him about that one time, with the horse—”
“And the garden gnomes—”
“—and the giant carrots—”
“—so many carrots, gave me nightmares—”
“—and then your dad’s old racing broom—”
“—oh, yeah, he was mad for weeks!”
“—best vacation ever!”
They both turn to Remus expectantly, the other half of the custard now completely forgotten in Sirius’s hand, and he finally manages a croaked, “What?”
“Animals hate me,” James offers by way of explanation.
“Yeah, he’s hopeless. Seriously.” Sirius smirks—this seems to be a common expression of his, Remus notices—and it takes Remus a moment to get the awful pun as James groans.
“Not again! What, did someone jinx you at birth to make that joke every five minutes? I swear, one of these days I’m going to disown you as my friend—no! I’ll disown you from acquaintanceship. I’ll be friends with—Say, what’s your name?”
“Er, Remus,” Remus manages.
“—Remus, he’s my new best friend, because I don’t know you.” Remus can almost hear the unspoken “So there” following his words.
“No, I saw him first, so he’s mine,” Sirius counters. “Besides, you’d think you’d be used to it by now; I’ve only known you since birth.”
“And yet you haven’t gotten any funnier,” James says dryly.
The conversation descends into pure bickering, and Remus surreptitiously slides The Secret Garden out from the inside pocket of his robes and picks up reading where he left off. Sirius sees him and winks, not stopping his tirade against, from what Remus can tell, James’s smelly feet. (“Good thing we’re sharing a room then, eh?” James replies.) Remus inexplicably turns red.
They don’t meet Peter—a small, inconspicuous boy with hands like birds, timid and fluttering, who takes one look at James and “falls in love,” jokes Sirius, wincing when Remus cuffs him over the head with Treasure Island—until arriving at the dorm after dinner, but it’s not long before they’re RemusPeterSirius&James and then The Marauders and the bane of McGonagall’s existence. Remus has noticed that Sirius has this habit of winking at him at the most inopportune moments—usually when lying to save their skins—and Remus will flush red because he has a horrible poker face and really, Sirius should know better. It only happens all the time, and they end up with twice as many detentions as they would otherwise because the teachers have taken to watching Remus for signs of guilt (which really is just not fair).
And once, after pranking the statues near the Great Hall to sing "Grease Lightning" whenever Snape walks by, Sirius grabs his hand running away from Filch and he almost feels like he can’t breathe. He spends the next hour in the common room, carefully absorbed in The Princess Bride (“Why do you read so many girl books?” James asks distastefully.) and avoiding Sirius’s grey-eyed gaze.
He’s not in love—he’s only eleven, after all—but it feels like the beginning of something.