There are three things you need to know about the Hogwarts Express:

One: It always leaves from Platform 9 ¾ at King's Cross on the first of September.

Two: The train always leaves at exactly 11am.

Three: Peter Pettigrew will, without a doubt, need to run for the train. every. single. year.

Sirius Black lounged at the last door of the train, ignoring the stares of some fourth-year girls who were standing a bit too close for his liking.

Upon hearing the tell-tale sounds of the steam circulating through the pipes of the scarlet locomotive, he stuck his head expectedly out of the window.

Smirking to himself, he saw his friend running as fast as his impossibly short legs could carry him, trunk trailing behind him for the seventh September running.

"Come on, Wormtail!" Sirius yelled in encouragement, flinging the door open to pull Peter and his luggage onto the train. As the mousy-haired boy collapsed onto the train steps, Sirius pulled the door shut with vigour, and picked up his friend's trunk. "Merlin's balls, Pete" he yelped, almost dropping the heavy object "I thought we talked about packing light after last year!"

Peter's smile was impossibly wide as he wiped his sweaty palms on his trousers. "Good to see you too, Padfoot."

Sirius pulled him into a one-armed hug. "Come on, mate, Prongs and Moony have bagged us a compartment."

Much to the joy of the fourth-year girls, Sirius demonstrated his strength and legendary broad shoulders by hoisting Peter's trunk up and carrying it in front of him, leading Peter to their friends a few carriages away.

James Potter and Remus Lupin were sat opposite each other in the compartment, both staring in wonder at a small golden badge in James' hands.

"James, I'm not being a wanker, but are you sure this is legitimate?" Remus' brow was furrowed in confusion.

"That's what I thought" the boy before him admitted, running a hand through his messy hair. "I mean, I've already got Quidditch captain and I've never even been a Prefect-" he cast a glance at his friend "sorry, mate, I thought you'd be a shoe-in for this."

Remus tried to play it off, but he couldn't deny there was a small bubble of envy in his stomach. He and James both knew it would pass. "It's alright, Prongs. I wouldn't have been much good as a Head Boy during my time of the month, would I? Personally, I thought Diggory was bound to get it."

James groaned in exasperation "but what does it mean?"

"I think it means that Dumbledore wants you to be Head Boy, James."

"But what about Quidditch? That's supposed to be my focus this year, Moony, I've got a great idea for a new formation that could really-"

"If you're talking about Quidditch for the whole train ride, I'm leaving" Sirius declared from the doorway, heaving a large trunk into the compartment that the pair could only assume belonged to Peter.

"Well, I've got a-"

"Yes, I know, a great idea for new arm exercises so that we can be better Beaters. Please let me be in the room when you tell McKinnon the good news, and we'll see if she can beat you to death with the bat before I can."

"Peter!" Remus broke the Quidditch talk by wrapping the last Marauder in a hug. "How was your holiday?"

Peter flushed with happiness at being reunited with his friends again. "Really good thanks" he turned to hug James "it was pretty hot, but the pyramids were really cool. I'd definitely love to go back one day and…Prongs, who did you steal that Head Boy badge from?"

"Close the door" James hissed. Sirius rolled his eyes and obliged.

"He's been losing his mind about it for the past two days" Sirius informed the group, nicking a piece of Remus' chocolate before sitting down next to the new Head Boy. "He's convinced it's a trick."

"But I thought Moony would be Head Boy" Peter admitted and, when Remus subtly elbowed him the ribs, he coughed and corrected himself: "I mean, congratulations, James. Do you know who Head Girl is?"

This elicited an even louder groan from James, who buried his head in his hands.

"It's Evans" Sirius beamed "bumped into Meadowes in the corridor earlier and she said the girls were celebrating before Evans and the Head Boy" he elbowed James pointedly "host their first meeting in the Prefects' carriage in an hour."

"What am I going to do?" James looked hopelessly at his friends. "I don't know how to be a Head Boy!"

Sirius shrugged "just let Evans do all the heavy lifting – she'll love it. She's been dreaming of this day since first year, mate."

Remus shot Sirius a warning look. "James" he said firmly "you can't let Lily do all of this on her own. Professor Dumbledore's chosen both of you for a reason – maybe it's his way of getting you to be a bit more…mature."

James' eyebrows shot up "Moony!" he admonished "I'm mature! I bought Denise Clearwater roses for Valentine's last year, I'm the highest scoring Chaser in Hogwarts history, and McGonagall said I could definitely be an Auror if I applied myself. What's more mature than that?"

"Head Boy" Remus said with a small smile, popping a square of Honeydukes caramel into his mouth before offering the distraught boy a line as a truce.

James accepted and slumped back into his seat. "Evans is going to kill me when I walk into that meeting, isn't she?"

"Moony" Sirius said seriously "I need you to memorise every single detail of it for us. For research."

"Duly noted" Remus grinned. "Now James, do you want us to polish your badge before the meeting or-?"

Sometimes, James Potter really hated his best mates.

"How do I look?" Lily Evans twirled in her robes for the Gryffindor seventh year girls, her gold Head Girl badge glistening in the midday sun.

"Very professional" Marlene McKinnon observed from where she sat cross-legged on the floor of the carriage. "But are you sure you've polished the badge enough?"

Dorcas Meadowes, who was plaiting Marlene's hair, slapped the blonde playfully on the back of the head. "Be nice" she scolded "Lily, you look lovely. Don't be nervous, everyone knows you were made for this."

"Do we know who the Head Boy is yet?" Alice Fortescue asked, fanning herself with the Helga Hufflepuff Chocolate Frog card she'd just acquired.

No one volunteered an answer.

"I'm just glad the Prewetts left last year" Lily muttered "can you imagine?"

The three girls nodded in horrified agreement. Lily had dated Head Boy Fabian Prewett for the majority of the girls' sixth year, undertaking the usual Hogwarts dating rituals of Hogsmeade trips, fumbles at parties and sneaking in trips to the Prefects bathroom as an excuse to get naked together. Lily, predictably, had found herself getting bored towards the end of the and, in a very unpredictable move, had broken up with Gideon, mistaking him for his twin, at a Gryffindor party two days before their NEWTs were due to start.

To say that Lily had kept her head down for the last few weeks of sixth year would be an understatement.

Marlene was still fondly recalling the memory of Lily tripping over her own feet on the stairs up to the dormitory, pissed on Butterbeer, having spent the remainder of the party dancing with half of the Gryffindor Quidditch team, when Lily cleared her throat.

"No matter" the redhead smiled "there won't be any time for boy drama this year. Head Girl and NEWTs? It's going to be a nightmare."

Dorcas snorted "everyone's going to need a shag at some point this year, Lils. You'll explode from the stress if you don't."

Lily pulled at face at her dormmate, straightening the collar on her school shirt for the last time, before running her hand down the length of her robes. "Are you sure I look okay?"

"Lily" Marlene stood up and took her friend's hands in hers "you look gorgeous but also a bit stern, like a sexy teacher, which is exactly what you need in a Head Girl. You're going to be amazing. This is your year."

"Go and knock 'em dead, Lils" Alice beamed, echoing Marlene's sentiment.

"Thanks, gang" Lily was momentarily flustered as she gathered herself. She squeezed Marlene's hands before dropping them. "I'll see you after the meeting, okay?"

"We're not going anywhere" Dorcas assured her, reaching out for Marlene's waist to pull her back into prime plaiting position.

"Good luck!" the trio chorused as Lily closed the door of the compartment behind her. Taking one last deep breath, she rubbed her slightly sweaty palms against her robes and held her head high as she made her way to the Prefects' carriage.

When she entered the carriage, it was surprisingly quiet. Usually, the room was filled with an excited buzz of all the Prefects catching up with each other about their summer or their plans for the year, but this morning you could've heard a pin drop.

She scanned the room and saw Remus sat with Rebecca Cole, a fifth year Ravenclaw who had just received her badge and was fidgeting nervously. Lily smiled at Remus, signalling that she'd catch up with him after the meeting. Although the pair had exchanged several letters this summer, she was keen to hear what he'd make of her posting.

As Lily made her way up to the top of the carriage, exchanging smiles and greetings with the majority of the Prefects as she went, she noticed with dread that Antonin Dolohov had returned for his final year as one of the Slytherin Prefects. Lily had had the misfortune of being paired with him on rounds briefly in fifth year, and had never quite recovered from the fear of him that, inexplicably, sat deep in her bones. She was hoping he might have just walked out of school and joined You-Know-Who already, but seemingly, no such luck.

She passed Amos Diggory who, to her surprise, had retained his Prefect badge. She was convinced that they'd have been sharing the Heads' office together this year.

"Congratulations, Lily" he smiled at her politely as she passed "very excited to see what the two of you are going to cook up for us."

"Thanks, Amos. Is the Head Boy here yet?"

The carriage silenced once more.

There was a cough to her right "here, Evans."

Lily's stomach dropped to the soles of her feet. She turned slowly, but she knew that voice anywhere. She would not let James Potter and his bloody Marauders turn today into a practical joke for her.

"Potter" she could barely keep the venom from her voice "kindly return that badge to its rightful owner and get back to your carriage. McGonagall will be distraught if I have to deduct points from you before we've even started the term."

The boy in question sat on a table, swinging his gangly legs out in front of him. His inkblot black hair was, as per usual, a mess, and he managed to look like he'd just rolled out of bed, even though Lily was fairly sure he'd just gotten dressed into his robes.

James took off his glasses and rubbed the lenses on his robes. He wasn't in the mood for a fight today. "It's my badge, Evans" he said softly "I can show you the letter if you like."

Lily was gawping at him. "Show me the letter" she demanded, flapping her hands at him in exasperation.

Everyone in the carriage held their breath as James wordlessly produced a letter with the Hogwarts seal on the back and handed it to the Head Girl. She scanned it quickly, her face falling with every line she read.

When she finished reading the letter, ended by Dumbledore's familiar signature, she looked across the carriage at Remus for confirmation, who nodded solemnly.

This was, potentially, the worst day of Lily Evans' life.

This was supposed to be her moment, and now she would have to share it with the imbecile who continually harangued her for a date, played obscene pranks on the entirety of the school, and cared about nothing but his stupid popularity and his stupid, stupid Quidditch team.

She was not going to let someone like James Potter ruin this year for her. It was too important.

Lily gathered herself and handed James his letter back, refusing to look at him in the eye. She ignored the titters from the back of the room as she addressed the room confidently: "Hello everyone, if you're not meant to be in the Prefects' carriage, please leave now" when nobody moved, she continued "my name is Lily Evans, and I'll be your Head Girl for this year."

"And I'm James Potter" James raised a hand in greeting to the room "I'm, somehow, Head Boy this year and will be helping Lily with whatever brilliant things she has planned for the school."

Lily couldn't control her eyeroll, earning outright giggles from the spectators in the room who had seen versions of this dance between the pair for years, but she ploughed on nonetheless.

"So, here's what I…we expect of you going forward…"

This might not have been the sort of year that Lily and her friends had been predicting back in their carriage, but it would be a year for some things: hatred, sex, love, pranks, parties and all-out war.

They just didn't know it yet.