I own nothing, much as I would like to. Enjoy! :D
"I don't like this. I don't like this at all."
The two boys huddled close together behind the banister at the top of the ornate staircase. The taller of the two frowned, pulling his patched cloak around him tightly and checking to see if anyone was coming from the corner that led to Gryffindor Tower. The other boy chuckled softly, tossing his soft black hair our of his eyes.
"They'll be here any minute now, stop worrying you idiot" he replied lightly, earning a soft punch to the shoulder from his friend. He turned to face him with a grin, looking away from the staircase for the first time since they had got there.
"Moony. How many times in the four, short-yet-glorious years you have known me, have we actually been caught? This isn't even half as bad as half the stuff we did last year!"
Remus rolled his eyes, still trying to shake the feeling of unease that usually accompanied him when he was dragged into his friend's various schemes. He dared a quick glance at the window behind them, where the sky was quickly darkening, bringing them ever closer to the curfew for fourth-years. Sirius followed his gaze and guffawed involuntarily, realising what the problem was.
"Curfew? Really? I suppose you're conveniently forgetting last month's 3am tour of the Quidditch fields, and last year's amazingly well planned midnight party in the astronomy tower, and-"
Not so soft a punch this time. Sirius scowled and turned back to stare down the staircase, rubbing his shoulder.
"You love me really..." he muttered, trailing off at the sound of faint voices approaching the bottom of the staircase. Remus tore his gaze away from the large window at the sound, turning away from where the moon was beginning to appear from behind a soft cluster of dark winter clouds. The gentle light filled the corridor as Sirius tapped his shoulder incessantly, shushing the indignant, and silent, boy.
"I've said it before and I'll say it again, Potter. I'm perfectly capable of walking back on my own."
"Ah, don't lie, Lils. We both know this is the highlight of your week..."
The two figures rounded the corner and passed through the tapestry that hung at the bottom, their footsteps ringing loudly on the flagstone floor. Sirius grinned – this had the potential to go far better than they had first expected. He pointedly ignored the furious whispering from Remus had started up in his ear (Sirius he's not with Frank oh god if we hurt Lily he'll murder us and you know it don't you dare do it Sirius, I'm not kidding-) and trained his wand on the staircase, muttering the short incantation under his breath.
James skipped up the stairs happily in front of the tall, disdainful looking girl, who shook her head at his childishly gleeful expression.
"So then Lils, now that we're alone, just what were you hoping for I'm sure, what do you say we – AHHH!"
Dancing up the stairs a short way up from Lily, James spun around to face her and felt his foot suddenly sink down into nothing. He twisted wildly, trying to turn back around, gain some balance, anything, and feel backwards heavily onto the staircase as the girl looked on in amusement. She walked on calmly, easily jumping over the space in the stairs where James sat, tugging fiercely at his helplessly trapped leg. He looked up at her sadly as she passed, struggling to hide her laughter.
"Don't suppose there's any chance of you giving me a hand up here, if not a date? Lily?' he called after her as she spend around the corner at the top of the stairs, shoulders shaking helplessly.
Sirius could stand it no longer. As soon as Lily's long red hair had swept around the corner after her, he burst out laughing and stood up to lean on the banister.
"Oh mate, that was smooth. Positively beautiful." he giggled, stretching a hand down behind him to casually help Remus up from the floor. James sighed, not even having to turn around to recognise the sounds of his two best friends from the top of the stairs. As they made their way down towards him he continued to stare forward moodily, ignoring Sirius' continued laughter until he and Remus sat down on either side of him. He looked at Lupin , expecting maybe just a little sympathy, but was dismayed to find the older boy also holding back a laugh.
"She's going to hate me forever, isn't she" he mused, as Sirius grabbed his shoulders and hoisted him out of the trick stair. He staggered as he stepped up to the next stair, staring wistfully up to the dim corridor.
"Oh, and I did mention I'm going to kill you, right?" James shook himself away from thoughts of Lily and turned to Sirius with a fierce glare, not surprised to see him already grabbing Remus by the hand and running up the stairs wildly, still laughing. He sighed, and ran after them, not bothering to give them a head start.
Over the next few months it became a common thing to pass by the fourth floor staircase and find a dismayed student with a leg or two buried in the missing stair, to the point where people began to warn each other and generally treat the staircases with slightly more caution than before. Several teachers puzzled over it for a while, before deciding that it must have simply been one of the little ways Hogwarts showed it's various oddities sometimes. Nobody noticed the two boys who seemed to instinctively know which stairs to jump, who always seemed to be the ones rescuing others who were trapped, and who could occasionally be found sitting on the large windowsill at the top of a staircase on the fourth floor, laughing and talking in the quiet of the empty corridor.
I always wondered about the origins of the trick step, so I wrote something silly to entertain myself, and hopefully you as well.