Every now and then, we have those moments that define us, for better or for worse - Sirius.

James' eyes passed over Marlene, subtly enough that she didn't notice anything but obviously enough that Sirius did. Sirius nodded slightly. James stood. Peter copied him. "I'm going to try to get that Charms homework done." Sirius nodded again. "I've had no luck with Potions though," James said, sounding distressed.

Sirius picked up on the cue. "I can't seem to get Transfiguration," he said, wrinkling his nose.

"Me either!" Peter said, sounding relieved.

Sirius and James' eyes met and then both looked away quickly. "If you'll help me with Potions," James said, "I'll help you with Transfiguration."

"Done," Sirius said.

"Come up around six?" James said. "I want to get to bed early tonight."

This of course, was the biggest lie yet. For starters, the Marauders generally did their homework early in the morning - though they were all up to date in preparation for tonight - and secondly, they were not planning to get to bed until early in the morning, if they slept at all.

"Me too," Sirius said. Marlene, who was listening in, pouted slightly. "There'll be other nights, McKinnon," he said, winking.

She raised an eyebrow and tossed her dark hair over her shoulder. "What makes you so sure, Black?"

Sirius watched James wave at an annoyed Lily Evans and then leave with Peter tailing him. Smiling, he leaned closer to the fourth year, so close their noses were almost touching. "I just know," he murmured. He'd perfected this.

Marlene blinked but she didn't back off like most girls usually did. It was one of the reasons they got on so well, as friends, or whatever else people dubbed them; he was a shameless flirt and knew it, but she was too and wasn't nearly as bothered by his antics as most others. She tilted her head slightly, bringing them even closer together - if that was even possible - and said, "Oh, really?"

"Really," Sirius said. He kissed the side of her mouth quickly, pulled away and stood.

"You're horrible!" she said, looking rather flustered.

"Is that a blush, McKinnon?" he asked. She scowled. "I think it is," Sirius said, feeling rather pleased with himself. "I don't think I've seen you blush since you were twelve."

"Clearly you haven't been spending enough time around me then," Marlene replied.

"That's fixable," Sirius said.

"Let's go then," Marlene said, her dark eyes meeting his boldly.

"Nice try. I'm free tomorrow though."

"What's her name?" Marlene asked.

"Homework," Sirius said.

"Sure, Black."

Sirius rolled his eyes. "Jealous, are you?"

Marlene laughed. "Not really. If you're busy, I'll have to make other plans. Oi! Morgan!" A boy at the Hufflepuff table spun around. "You doing anything tonight?"

Sirius cast a non-verbal jinx at the boy, who shifted uncomfortably on his seat. "Er..., yeah, actually," he muttered. "Sorry."

Marlene wasn't stupid. Sirius supposed he should have left it at boils; the pink hair was overdone. "Now who's jealous?" she asked.

"Still you." Sirius winked, gave her a cheery wave, and left. He knew she was watching, so he stopped to talk to Julianne Price on the way out of the hall.

She blushed - as she always did and next to her, Katelyn and Sylvia giggled. "Hi, Siri," she said, batting her eyelashes. Lily Evans and Mary MacDonald rolled their eyes a little further down the table; Mary was pretending to retch into her potatoes and Lily was choking on her pumpkin juice, trying not to laugh.

"Please, please don't call me that, Jules," Sirius said with a grimace. She blushed again.

"So what do you want?" she asked sweetly.

"Just to say hi," he said, shrugging.

"I think you've just made her day," Marlene said. Sirius hadn't heard her approach and only just managed not to jump. She continued right past him and sat down with Lily and Mary.

Julianne sent Marlene a nasty look and shifted. "Are you busy tonight?"

"Very," he said gravely.

She looked annoyed and glanced at Marlene. "How about tomorrow?"

"He's busy tomorrow too," Marlene said, shooting Sirius a coy smile. "Aren't you?"

"Very, very busy," Sirius agreed with a grin. "I'll see you later, Jules."

"Bye, Siri," she said.

Sirius gritted his teeth, waved and left, for real this time. "Siri! Wait up!" a new voice called mockingly when he reached the entrance hall.

"Sod off, Snivellus," Sirius said, rolling his eyes. He bolted up the staircase, taking the steps two at a time and when he heard footsteps behind him, ducked into a side-passage that would take him to the fourth floor. Footsteps still came after him.

Sirius let out a growl and without even bothering to turn, aimed his wand over his shoulder and gave it a quick jab. There was a yelp of pain and then he did turn and was vindicated to see Snape pink-haired and covered in painful looking boils. It was his favourite hex, lately.

"Sod off," Sirius told him.

"I live here too," Snape said, waving his wand to fix his boils. "I'm just as entitled to walk here as you are."

Sirius rolled his eyes, spun on his heel and shoved Snape out the way as he doubled back the way he'd come. He was annoyed but not surprised to hear footsteps behind him. He gritted his teeth. "I thought you were walking the other way."

"I changed my mind," Snape said smoothly.

"Only because I changed my mind first," Sirius growled. "Bugger off, Snivelly, before I make you."

"You can't make me do anything," Snape said, following Sirius down another corridor. "I know you're up to something, Black and I'm going to find out what."

"Yes," Sirius said, turning. "You've caught me. I'm up to something. Happy? Now bugger off back to the dungeons and stop bloody stalking me!"

"I'm just walking," Snape said.

"LEAVE ME ALONE!" Sirius said, fed up. He turned, brandishing his wand. One wave later, Snape was dangling from the roof of the corridor by his shoelaces. His pasty face was turning a splotchy red colour and whether that was from embarrassment or from the blood rushing to his head Sirius didn't know or care. Snape flapped his arms, trying to get his wand out of his robes. He looks like a bloody bat, Sirius thought and made a mental note to tell James.

"Off to find Lupin?" Snape called at his retreating back. Sirius ground his teeth together, but ignored him. There was a thump and a quiet "oww!" and then soft footsteps ran after Sirius; Snape had left his shoes on the ceiling and was just wearing his socks. "Because he won't be there."

"I know he won't," Sirius said curtly.

"I saw him," Snape said.

"I bet you did," Sirius muttered, checking his watch.

"He was with Madam Pomfrey."

"He's sick," Sirius said. "Now shut up and go bother someone else."

"She took him into the Whomping Willow," Snape continued. "I thought that was a rather odd place to take a sick person."

"Yes, well you can keep your thoughts to yourself, if you wouldn't mind."

"There's something not right about Lupin," Snape said nastily.

"You're one to talk," Sirius told him.

"He's unusual. All the teachers like him, but I think they pity him too."

"I'll make you pitiable," Sirius promised him.

"You can try," Snape said, twirling his wand. "So why did Lupin go to the Whomping Willow?"

"Why are you obsessed with him, hmm?" Sirius said. He caught Snape by the throat and slammed him against the wall of the corridor. "What business of yours is it?"

"I'm just curious," Snape choked, his long-nailed fingers scrabbling to prise Sirius' hand off. Sirius let him fall. He slid the ground, gasping.

"Yeah? Why don't you let me worry about my friends and you worry about yours. Or don't you have any after you pissed Lily off?"

"I'm just concerned for the well-being of my classmate," Snape said, getting up again, but he'd gone pale at the mention of Lily.

"I'd worry about your own well-being," Sirius advised. "Particularly if you keep bothering me."

Snape shrugged. "If you hurt me, I'll have no choice but to go to the Hospital Wing. And if Lupin's as sick as you say he is, I might even get the chance to see him. I'm sure he'd tell me why he went to the Whomping Willow."

"I'm fairly sure he wouldn't," Sirius said, turning suddenly. There were about seven secret passages in the vicinity, but if he used one now, Snape would learn about it.

"Oh, so it's a secret?" Snape asked.

"Yes," Sirius said. "A huge secret. Bigger that your nose."

"My nose isn't that big," Snape said, having not noticed Sirius' non-verbal Engorgement Charm. At least not until it started to pull his head down. "But a secret, you said? Is it a good one? Or a bad one? Because I'd hate to see you get expelled." His nose was now the size of a loaf of bread and he was having trouble walking.

"I'm sure you would," Sirius said. Snape tapped his massive nose and it shrank back to its normal - though still rather large - proportions.

"Have you ever been in the Whomping Willow?" Snape asked as he followed Sirius.

"No," he said.

"Liar," Snape hissed, looking gleeful. "I saw you last time Lupin was 'sick'. You and Potter and Pettigrew were sneaking around the grounds."

"If you knew the answer, why'd you ask the question?" Sirius asked, thoroughly fed-up.

"To see how big of a secret it is," Snape said.

"I already told you," Sirius snapped. "It's a massive secret."

"Obviously, if you lied about it. So are you going to tell me?"

"Why the hell would I do that? You're the biggest pain in the arse I've ever had the misfortune to meet - and with my family, that's saying something - and you'd like nothing better than to get us all expelled."

"Why would I want you expelled?" Snape asked.

"Because you're a jealous little bastard," Sirius said. "That's why. You can't stand that James is better than you are, at everything. You're scared you'll lose Lily to him. I've seen the way you talk about him. It's sick. It's like you're trying to brainwash her or something. And Remus, you don't like him because... well, I don't know why. But I suspect it has something to do with him being one of the nicest people here because it makes you look like even more of a foul, utterly unlikeable wart than you already are."

Snape's expression could have curdled milk. "And you?" he asked. "Let me guess? I'm jealous of you too."

"Snivvy, I think you're jealous of everyone," Sirius said. "But if I had to guess your reasons concerning me, it would probably be because I can fly in a straight line when I'm on a broomstick, because I've kissed more girls than you've ever talked to and because I know how to use a shower."

"I think you think too much of yourself, Black," Snape said.

"I think I was under-exaggerating, actually," Sirius said. "I left off that I know how to open a shampoo bottle." Snape flushed an ugly pink colour. For a second, Sirius thought he might have crushed his confidence enough that he'd slink back to the Slytherin Common Room and stay there for the rest of the night, but he was sadly mistaken.

Snape looked up, his yellow teeth bared in a smile. "Is that what Lupin's doing in the Whomping Willow? Learning to open shampoo bottles?"

Sirius snarled. "No, Snivellus."

"Then what is he doing?"

Sirius threw his arms up. "You know what? If you're so damn interested, why don't you go see for yourself?"

Snape's face soured. "I can't. The tree... Davey Gudgeon, remember?"

"There's a knot," Sirius said, frustrated. "Find a long stick and give it a prod." And then, Moony will eat you and you'll never bother me again, he thought happily. He chuckled at the thought. And then he frowned. No, wait...

"The tree?" Snape asked. "Poke the knot on the tree?"

No. No, no no. Moony'll kill me. And Snape. And then Moony'll kill himself. "That's not what I said," Sirius said, tripping over the words. "I take it back."

Snape smiled. "Too late for that."

Oh, no it's not, Sirius thought grimly, pulling his wand. "Obliviate!" he shouted, but Snape dove out of the way and took off running, his robes flapping behind him. Sirius chased him, still trying to clear his memory of the last few minutes but Snape was too quick, blocking the spells. "Sniv- Snape, wait!" Sirius shouted.

"Nice try, Black," Snape called, still running. "Pedis Offensio!"

Sirius didn't get his wand up in time and fell flat on his face as the Tripping Jinx hit him. Damn. Damn, damn, damn! Sirius pushed himself up off the ground and fumbled with his mirror. "James Potter," he said, his voice shaking as he ran through the corridors.

"Padfoot?" James asked as his face swum into view, framed by the boy's dormitory. "Where are you? Wormtail and I have been waiting for ages."

"Prongs, I fucked up," he said. "B-badly."

"What happened?" James asked sharply. "Where are you?"

"Just-just coming into the Common Room now," Sirius told him.

"Password?" the Fat Lady asked.

"Poppycock. Jamie, I didn't mean to, I swear!" Sirius was running now, taking the stairs to their dormitory two at a time. He reached the fourth landing and shoved the door open.

"Didn't mean to do what?" James asked, his voice coming from the mirror and from James himself, who was sitting on his bed, tying his shoelace.

Sirius threw his mirror down onto his bed and turned to James. "I didn't mean to," he half-sobbed. "Moony- I told Snivellus- the Willow."

James' expression turned deadly. "You did what?" he asked.

"I told him - Snivellus - the knot and the tree and then he ran-"

"Snape's gone to see Moony?" James asked. Sirius didn't think he'd ever seen him looking so angry. Peter, who was sitting on his bed, just looked scared.

"I'm sorry!" Sirius cried.

James tore out of the room without another word. Probably off to tell Dumbledore, Sirius thought miserably. "He forgot his other shoe," Peter said, bemused.

"Right, now, Wormtail," Sirius snapped, "I don't think he gives a damn." Sirius wanted nothing more than to sink into the ground. James surely hated him and come morning, once Remus found out what happened, he would too. Sirius lay there, wallowing in self-pity until something clicked in his head. He sat upright.

James wouldn't have gone to get Professor Dumbledore. There wasn't time. Not in James' mind, anyway if Sirius knew James half as well as he thought he did. He's gone to save Snivellus, Sirius realised, taking a shaky breath. His eyes fell on James' bedside table. There was a Quidditch magazine, an unopened box of Bertie Bott's Every Flavour Beans that he'd put there to tempt Sirius, an Godric Gryffindor chocolate frog card and James' wand.

"No," Sirius breathed. "Prongs, you've got to be the world's biggest prat!" He snatched the mahogany wand up and sprinted out the dormitory door.

He didn't stop until he reached the first floor, whereupon he burst through Professor McGonagall's office door. "Mr Black!" she cried, so shocked she'd upended a bottle of ink on the letter she was writing.

"No time, Professor," he gasped, clutching his side. "Snape knows about Remus. He's gone down there. I told him how to but I didn't mean it! James went to stop him but he doesn't have his wand." Professor McGonagall was gaping at him. "Professor, please!" Sirius shouted.

"But students aren't supposed to know," she said, blinking.

"That's not important right now!" Sirius bellowed.

She nodded and picked up a quill. Headmaster, she wrote. Sirius didn't wait to see what would come next. Convinced now that she would alert anyone that needed to know about the incident, he took off again, after James. "Mr Black!?" he heard behind him.

"Not now, Minnie!" he shouted.

"MR BLACK, COME BACK IMMEDIATELY!"

"I WILL! IMMEDIATELY AFTER I'VE HELPED JAMES!" And then he was out of hearing range. He ran through the Entrance Hall - eerily, he was the only one around, so every footstep echoed - and burst through the doors and onto the grounds. "Prongs?!" he hissed, not really expecting an answer. Still, he was worried when none came.

He froze the Willow without breaking his stride and threw himself through the gap at the base.

Some would call him stupid, vain, or arrogant, or maybe all of those things. Those who knew him better would call his arrogance confidence and say that this made him reckless, but that that he was too bright to be stupid. And then they'd probably chuckle and agree that yes, he could be vain.

These groups of people - friends, acquaintances or enemies - would all agree on one thing, however. Some would do so grudgingly, followed by a snide remark about this making him weak, some would shrug and nod, while others would grin and cheekily suggest it was a side-effect of his Animagus form; Sirius Black was a lot of things, they'd tell you, but he was not, ever, disloyal.