A/N: Written for a Tumblr prompt - Skimmons Hogwarts AU. The idea ran away with me so this has turned into a multichapter fic. I couldn't resist.

Disclaimer: HP and Marvel aren't mine, unfortunately.

Chapter One

Fitz was used to the chill of autumn in the Scottish Highlands. Although he had grown up just outside of Edinburgh, he had always found it reassuring that the boarding school he'd been invited to attend on his eleventh birthday wasn't that far from home. In fact, compared with the majority of the students at Hogwarts School of Witchcraft and Wizardry, he was practically a local. The only downside to this was that he had never been on the Hogwarts Express for the entirety of its journey from King's Cross in London to Hogsmeade Village, just south of Hogwarts castle. Instead, on the first of September each year, he disappeared through platform 4 ½ in Edinburgh Waverly station and met the train for the last leg of its journey. There was never more than a handful of students waiting there (all northerners) and he'd been concerned that it would be much harder to make friends. He needn't have worried.

The windows in the library had started to frost on the outside, a sure sign that they were going to get snow soon, and Fitz thanked Merlin that the old castle wasn't anywhere near as cold as it should be. Ah magic, how he loved it. Sighing, he rubbed a hand across his face and turned back to his potions essay. Fitz was a genius and he had the grades to prove it, but potions was not his best subject. Not for the first time that afternoon, he wished that Simmons was holed up in the library with him. Unfortunately, she was running about the castle grounds with Professor May. Something was killing the unicorns in the Forbidden Forest and Simmons had a theory. She'd practically sprinted off to the fourth floor to talk to May - their Defence Against the Dark Arts professor - when they'd finished lunch. Instead, he had Skye sitting across from him. It wasn't that he didn't like Skye, she was his other best bud, it was that she was even worse at potions than he was.

'Fitz, please tell me Simmons will be back soon,' Skye sat up quickly as the librarian hobbled past, scowling at them suspiciously. Skye had been using her copy of 1001 Plants & Fungi as a pillow.

'She said she wouldn't be long but y'know how she gets. She's probably giving May a lecture about the fascinating cell structure of unicorn hair or whatever.' He paused to search for his biro and found it under a sheaf of notes on the restorative properties of flobberworm mucus. 'I mean, it is fascinating…'

'But our crappy essays really need her.'

'Yup.'

They fell back into a reflective silence. Skye gazed about the bookshelves and absentmindedly shredded the top sheet of her essay. She'd regret it when she had to copy it all out again. Well, she wouldn't actually do it but she'd feel bad for a second while she considered the extra effort it would take. A few decades ago, the whole school had still been using quill and ink. Essays were written on thick sheets of rolled parchment, the kind you see in old films about Elizabethan England. They'd only updated at the insistence of a Hogwarts alumnus who'd joined the Ministry after graduating. Ms Granger had done a lot of things to reform the wizarding world but Fitz and the other muggleborns thought that being able to use proper pens and paper was probably the most appreciated.

Skye was thinking hard, though not about her potions essay. She was currently weighing up her team's chances of winning their upcoming quidditch match. It was the first of the season and, though she'd been on the team for the past six years, it always made her nervous. As a seventh year, this would be the last chance she had of helping the team win the quidditch cup. Slytherin hadn't won in a long time, Gryffindor always seemed to pip them to the post at the last minute and it stung. It wasn't even that their players were that much better than the other houses, they just had an abundance of confidence that seemed to buoy them to victory.

She wasn't the only one who'd been suspicious, a few of her teammates were convinced that the Gryffindor team were cheating and had even spied on their practices. All they'd found out was that the Gryffindor captain had a splinter from Viktor Krum's broomstick. Apparently, he'd gotten it from his uncle who'd been there when Krum barrelled into the stands while chasing the snitch at the 424th Quidditch World Cup in 2002. After that accident and Bulgaria's spectacular defeat by Egypt, Krum had then resigned. The entire Slytherin team had wondered whether the splinter could've been more than a good luck charm. If so then now that the captain had been replaced, this could be their year.

The pair's wandering thoughts were interrupted when a breathless and pink-cheeked girl plopped down in the remaining chair at their table. Simmons set her satchel down and unwound the striped green scarf from her neck while she grinned at her friends.

'I definitely know what's killing the unicorns!' Her hair was coming out of its neat ponytail and when Skye looked closer, she could see mud splattered up Simmons' robes.

'I hope you cleaned your boots, you'll get lynched if you've tracked mud all over the library.'

'Of course I did,' Simmons yanked the hem of her robes up to her knee and stuck her leg out at the other girl. Her sturdy black boots and thick tights were spotless. Evidently she'd cast a quick scouring charm on the way there.

'What is it then?' Fitz had stopped doodling a particularly cute monkey on the back of his notes and was now looking at Simmons with rapt attention.

'An erumpent.'

'Hang on, you think there's a class four beastie roaming around the forest and nobody has noticed, despite the fact it's the size of a rhino?' Fitz' brow furrowed.

'Yes. Considering the size of the forest it's not that unlikely-'

'Erumpents are native to Africa though,' Skye slumped over her essay again and rested her chin on her forearm. 'How did one get here?'

'Well, that's something that's up for debate but it is most certainly an erumpent. Not only were the unicorns, erm, exploded to death..? But the remains had traces of purple mottling on the skin. Now, we all know that erumpents secrete a fluid which, aside from causing explosions, also causes purple mottling where it comes into contact with skin.'

'I suppose they are the only thing fast enough to get a hit on a unicorn.'

'Exactly!'

'But you've no real proof, unless you can analyse the remains for traces of exploding fluid-'

'Already waiting on the results, Professor May and I stopped by the potions lab. Professor Banner said he'd send for me once the results come through.' Simmons was practically vibrating in her chair by the time she'd finished speaking. Skye thought it was incredibly endearing.

'Well, what's the plan when the results come back? Are they going to send a team in from the Ministry?'

'That's where you come in Fitz, I told Professor May about your CVVT things and she said it'd be a good idea to set some up near the sites where the unicorns were found. That way we can get a look at it before sending for a team.'

'CCTV,' he looked thoughtful and Simmons knew he was considering the benefits of taking his invention on a test run. 'Well, I suppose it couldn't hurt.'