DISCLAIMER: All things Hogwarts-affiliated belong to JKR, without whom I could not have written this, so it's the same ol' song and dance – not mine. Cover art by viria13.

Someone on Tumblr requested a Blackinnon drabble, so here I am, complying that request and incorporating a little bit of Jily, too. I sort of failed in the "drabble" sense, but… Look, a one-shot with an incredibly long-winded title! Stop judging me and read it.

An Accidental Implementation of the James Potter Dating Method

"Oh, for the love of – Sirius, just go talk to her."

"What?" Sirius Black blinked innocently from behind his Transfiguration book, which he'd been peeking over every ten seconds to look at something – someone, rather – across the courtyard. He didn't think he'd been all that noticeable, but of course Lily bloody Evans noticed everything, especially when she could use it to torture him.

Lily crumpled up the parchment she'd been doodling on and threw it at his head. "You know what," she said. "I know you're pretty, Sirius, but that's no excuse for being so incredibly thick."

"Hey!" James pouted at his girlfriend. "Don't call my mates pretty, Evans, or you'll wound my delicate self-esteem."

Remus snorted. "I think Lily's established over the past couple of years that your self-esteem is anything but delicate," he pointed out dryly. "In fact, I think your ostensibly indelicate self-esteem was precisely what made her hex you so much."

"I maintain that the hospital visits were a manifestation of the sexual tension between us," James said, failing in his attempts to appear haughty.

"Better watch it, Prongs," Peter warned, exchanging a wink with Lily. "She's got her wand out now. Bet she'd be willing to manifest some more."

"Too right, Pete," Lily affirmed, jabbing James in the ribs with her wand before turning back to Sirius. "But back to you, pretty boy."

Sirius rumpled her hair up with the affection a brother would bestow upon his little sister. "Aw, Evans, you're making me blush."

"Shut up." Lily swatted his hand away. "If you've got something to say, go say it to Marlene. I've caught you staring at her at least a dozen times; I know you want to go over there. Talk about sexual tension, you're killing me here."

"Padfoot's got a crush, doesn't he?" James smirked at his friend. "How cute."

Remus grinned. "Dare we call it puppy love, Prongs?"

"Shove it." Sirius scowled at the pair of them. "Especially you, Mr. Hey-Evans-Will-You-Go-Out-With-Me?. You've got no room to talk."

"Oh, I don't know about that…" James stretched luxuriously before dropping an arm around Lily's shoulders and pulling her close, looking pointedly down at her. "I might have a little room."

"I agree with these two," Remus said, more seriously this time. He pointed from James to Lily and back again. "Merlin help me, but I do."

"Seconded," Peter offered next. "Or thirded – fourthed? Whatever." He waved a dismissive hand. "Hear, hear."

Sirius threw his hands up in a gesture of defeated exasperation. "And what, exactly, do you want me to say to her?" he demanded of the group. "I'm not exactly on McKinnon's radar, am I? Disgraced, estranged Black that I am, she's a little too good for me," he added with a touch of malice. "At least, I'm sure she'd think so."

"Hey." Lily balled up another piece of parchment and threw that at him, too. "Don't be such a twat, Sirius; Mar's my friend, and if you keep talking like that, then yes, I'd have to say she is too good for you. As it is, though, I'm inclined to say that you're about par, so shut your trap and go talk to her."

"I hate to point this out, love, but that's a bit of a contradiction –"

"Sod off, James."

Tired of the debate and tired of his own inner battle of Should I or shouldn't I?, Sirius snapped his book shut – not like he'd been reading it, anyway – and hopped down from his seat on the wall. "Fine," he said. "Fine. If it will shut the lot of you up, I'll go talk to her."

"Right, I bet that's why he's doing it," James was saying as Sirius walked away, but he only responded with a rude hand gesture and continued on his way.

Marlene McKinnon was sitting alone, balancing a book on her knees and scratching out an essay. Her brow was furrowed, and one corner of her very red lip was pulled between her teeth as she attempted to concentrate on her homework. But Sirius had never cared much about homework and didn't understand how it took so long for anyone to get through it, seeing as how he and James could knock it out in one sitting, so he didn't feel too guilty for interrupting her.

"Hey, McKinnon."

"Black," Marlene said, looking up just in time to see him flick the hair out of his eyes. Her lips twitched. "You need a haircut."

"I'll make you a deal. I get a haircut, you go out with me," Sirius said without thinking, then cringed inwardly. Blimey, he sounded like James…

Marlene allowed herself a short laugh, thinking along the same lines. "Have you entrusted your pick-up techniques to Potter now?"

"Not exactly." Sirius rolled his eyes in an attempt to regain his composure. And to think, if he'd just been a little more inconspicuous, Lily would have left him alone and he wouldn't be stuck in this situation at all… "He's just rubbing off on me. Completely unintentional."

"I'm sure." Marlene doodled on the edge of her parchment, her eyes scanning her essay as she tried to think of something else to say. "So did you just come over here to harass me, or did you have something of consequence to say?"

"Between the two?" Sirius shrugged. "I s'pose I came over to harass you."

Marlene fought back a smile. "I see."

They were quiet then, Sirius wracking his brain for something to say, something to egg her on so he could keep the conversation going. He was usually cool, smooth, self-assured, but then he supposed that a pretty girl could really upset a bloke's normal mental faculties; James had been making that argument for years and Sirius had brushed him off, but now… Well, maybe this was that karma thing.

"What's the matter, McKinnon? Too good for me?" he said, exuding a confidence he didn't feel as he voiced the very thing he'd pointed out to his friends just a few minutes ago.

"Yes, but don't feel bad." Marlene patted his hand sympathetically. Hmm… Sirius Black did have quite nice hands. "I'm too good for most people. But, you know, about a hundred other birds fancy you. Why don't you try one of them?"

Sirius shrugged again. "Not interested."

"Because they are?"

"Something like that."

Marlene shook her head and crossed something out in her essay. "I know the thrill of the chase worked out for Potter in the end, but I wouldn't hold my breath if I were you."

"That so?" One of Sirius's eyebrows piqued with his curiosity. "And why's that?"

"Because…" Marlene faltered. She really had to think of a reason; she didn't have one, and in fact she would have liked to say yes. Much as James seemed to be rubbing off on Sirius, Marlene suspected that some of Lily's formerly cool façade had settled into her. Besides, Marlene McKinnon had always appreciated when someone worked for it, whatever it may be. "I think it would be a bad idea."

Sirius grinned. "Yes, it would be."

Marlene shot him an exasperated look. "You're impossible."

"You know that's Lily's favorite endearment for James, right?"

"I already told you, the James Potter dating method isn't going to work on me."

"Hmm…" Sirius pretended to consider that. "Lily said that, too."

Marlene picked up her book and smacked him with it. "What do you want to go out with me for, anyway?" she wanted to know. "You think it's enough to just ask, well, it's not. For all I know, you've got Galleons riding on this and it's just one big joke to you."

"I don't bet on people, McKinnon," Sirius said, ignoring that nagging little reminder at the back of his mind, the one telling him that he'd won five Galleons off Peter when Lily went out with James on Halloween. That was different. "I'm not a barbarian."

"Oh, please." It was Marlene's turn to roll her eyes to reestablish her cool. Sirius Black was an expert in riling people up, and Marlene McKinnon had always been easily riled; the two of them were an explosive combination, really. "And you still haven't answered my question, by the way."

"I know." Sirius flicked his hair out of his eyes again. Shit, maybe he did need a haircut. "But I don't really have an answer."

Marlene wasn't sure why, but her heart fell a bit when he said that. Or – all right, she knew why, but that didn't mean she had to like it. It was a very unpleasant feeling to begin with. "Well, see," she said, "then you probably don't really want to go out with me in the first place, not really."

"Hey, sure I do," Sirius said, a little indignant at being told what he wanted from someone who wasn't him. She wasn't looking at him, so he acted on impulse and clasped his hand over one of hers. "Listen, McKinnon, just because I don't know why I can't quit bugging you doesn't mean I want to bug you any less."

"I think –" Marlene began, but Sirius cut her off.

"Yeah, you've told me what you think," he interjected before she could offer up anymore bollocks protestations. "Now it's my turn. I didn't even want to come over here, but I did because my mates were bugging me, even though we all knew this was going to happen. But the thing is, McKinnon, I still want to go out with you, and I haven't tried to rationalize it because I'm too busy telling myself that it doesn't matter, that you're going to turn me down no matter what."

"Not no matter what," Marlene argued, looking at him then. Her hand was almost uncomfortably warm beneath his, sweating out her nerves. "But you can't even tell me why you fancy me enough to ask, so it seems to me that you don't really care."

Sirius released a short, aggravated breath and absentmindedly tightened his hold on Marlene's hand. "I do, though," he said. "I care enough to come over here despite my better judgment, don't I? I care enough to take a few kicks. Maybe you're right – maybe I've just been around James too long to know any better, but I care, anyway.

"And, okay, maybe I don't know you well enough to know why I want to go out with you," Sirius went on, admitting at least that much. "But don't you think it's just a bit more important that I want to get to know you, that I'll stick around long enough to figure out why?"

Marlene opened her mouth to say something, lost track of it, and closed it again. She didn't really know what to say to that, that was too good. In logic and sincerity, that was just too good for Marlene to turn down, especially since she hadn't really wanted to turn it down to begin with.

So instead of shutting him down for a final time, Marlene nodded. "Okay," she said, and smiled. "You really know how to wear a girl down in just the right way, don't you, Black?"

"Yeah, well…" Sirius returned the smile and his ribcage was relieved from the pain his erratic heartbeat had been causing it. "I learned from the best."

Across the courtyard, James turned to Lily. She knew the dynamics of Sirius-and-Marlene better than the rest of them, so he figured she'd have the best answer to his question: "What d'you reckon's happening over there?"

Lily smiled. "I think," she said, linking her fingers through his and meeting his eye with a twinkle in her own, "that somebody else just fell for the James Potter dating method."