A piercing yell echoed through the corridors of Hogwarts, followed by shouts and an offended American accented voice claiming innocence of all crimes of which the owner was being accused.

The voice belonged to Captain Jack Harkness, resident ghost of Slytherin house.

The yell belonged a disgruntled seventh-year boy, who had discovered the ghost hovering in the shower room.

This was the fourth time this week.

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Clara Oswald was not having the best of days. Her Advanced Charms textbook had flown off and was now hovering around the ceiling, her dorm mate Rose could do nothing but giggle about it (Rose was fond of giggling and not understanding why Clara did extra Charms study), and now Colin was complaining to her about the misdemeanours of one of his fellow ghosts.

"...and just like that, he floats right into the showers! Completely out of order, students are complaining, he started GIGGLING, apparently..."

"What? Sorry, I'm kinda busy here. Floating textbook issues." Clara was balancing precariously on a stack of books, attempting to net the rogue one with hastily shouted spells. "Accio textbook!" The Charms book merely dived out of the spell's range and drifted to the other side of the room, where it hovered, looking as smug as it was possible for a book to look. Which was rather smug, considering.

"Oh for goodness sake, girl, this matter is far more pressing than your homework..." Colin floated in front of her, glowingly coloured coat flaring indignantly. "A ghost cannot be allowed to do this! I have consulted Martha and Donna and they agree. You, my girl, are the only one in this school with the right talents for the job."

"Colin... BUSY!" Clara jumped off the stack of books and ran up to the taunting textbook. "You get down here or I will call the librarian!" The book froze in it's smug fluttering at these words, and drifted contritely onto Clara's bed, not before flapping a sulky page in her face on its way down. "THANK you! Now, what was this about a ghost, Colin?"

"Come on, guys, I wasn't doing any real harm... Ya don't need to get a firstie in to 'sort me out'..." Jack floated in the firm grip of Martha and Donna, the house ghosts of Ravenclaw and Hufflepuff respectively. They had cornered him spying on seventh years for a fifth time, and they had decided that, enough was enough. No more apologies.

Colin drifted in, accompanied by Clara carrying both her wand and a very angry look.

"Clara! You came!" Martha greeted the first-year warmly and gestured to the protesting Captain. "Colin said you could help?"

"I have an idea, yeah..." She aimed her wand at Jack, who looked slightly alarmed and started complaining at the ghosts again.

"Really, guys? You're gonna let Little Miss Firstie point THAT thing at me?" He struggled against the ghosts' grip again, earning him a sharp glare from Donna.

Clara thought for a second, preparing a spell in her mind. "Laetus Viridis Musica!" A stream of green sparks flickered over the Captain's form, skipping over his ghostly skin and sinking into him. Martha and Donna let go of him after a quick glance to Clara.

"What the hell did that do?" Jack glanced over his body, checking to make sure everything was in order.

"You'll see!" Clara grinned and strode off back down the corridor, determined to make the most of that Charms textbook she'd managed to subjugate.

#•#•#•#•#•#•#•#•#

Two days later, Jack hadn't bothered the seventh years and he was getting rather bored. Playing pranks on teachers with the resident poltergeist, Frobisher, just wasn't cutting it anymore. He decided that tonight, he would sneak down to the showers again, regardless of the incident with Clara. What would a first year know about this kind if advanced magic, anyway. Sure, she'd managed to turn Colin's coat back to its original, horrifically blinding colour, but that was different.

He floated quickly down the corridor, ducking into the wall as a group of chattering fourth-years rounded the corner.

It was when he got to the shower door that things got bad. A green glow lit his entire body, bright and clear, and a song started playing, apparently emanating from his very skin. It was...

Oh no.

She hadn't.

The Monster Mash.

Captain Jack Harkness had no choice but to stand and meet his excruciatingly embarrassing fate as two seventh year boys (why were they even in the showers together damnit) stuck their heads out of the door and caught sight of him, glowing brighter than a Christmas tree and blaring corny Halloween songs loud enough to wake the dead.

Funnily enough, he didn't go near the showers again.