"So, hypothetically, can you hide someone's identity with a Fidelius charm?" Asked James after the bell rang. They had stayed behind to ask Professor McGonagall some questions.

"I- well, yes, to a certain extent-"

"So say we were at home, could we give our name or picture or something to our parents so only they will be able to see us? Or does it not work that way?" Sirius continued to question her.

"Just how hypothetical is this? Well...yes, one's self would be the secret keeper, obviously, and anyone who has your name written down will be able to say your name, see you, and therefore say your location aloud, hypothetically. Anyone else would look straight through you."

"Ah ha! Perfect, thanks Professor. That's just what we need." Smiled Remus, who grabbed his notes. "Hypothetically of course." He added, grinning.

"Bye bye Minnie!" Both boys called, heading out of the classroom, talking loudly down the corridor. Minerva grabbed a goblet from behind her desk and took a sip of pumpkin juice. She was debating whether to go and make Dumbledore aware of their hypothetical plans, but decided it could wait. She would just have to make sure that she looked out for them more than usual.

oo0O0oo

"So that settles it then. As soon as we leave Hogwarts for the holidays, including when we sneak out to Hogsmeade, we can just Fidelius ourselves so no one knows where we are, although we won't need that so much here, we have the cloak to hide from Peter, plus the map," said Remus, looking up from his book under the tree by the lake. 

"That way there is no way he can rat us out to Voldemort or someone in his league when we aren't expecting it. The only remaining question is: do we let anyone else know what we are doing? There is no way in hell that Minnie isn't suspicious, so it's probably better to let her know the truth. Um... our parents will obviously know, and er...what about Lily?"

"Hell no. She doesn't need to know anything about this. No way." Objected James, startled at the mere thought.

"Well... don't come to me when she's more suspicious than normal about us."

"Fine, well apart from that, no one else really needs to know."

"Next question: do any of you know how to cast a Fidelius ? Because I have no clue." Grimaced James.

"Please don't say library, anything but the library..." Sirius whispered under his breath.

"Looks like a trip to the library then." Smiled Remus.

"No! Why? What's the need?" Sirius whined, now lying across the floor in disgust. "You can't make me, you can't!"

ooO0Ooo

Remus pushed open the thick oak doors, revealing countless large shelves of books and scrolls. James followed him, looking for the spells section, whilst Sirius crawled across from behind. "Why are you putting me through this torture? This is worse than one of those stupid detentions that Slughorn gives us. I don't want to be here!" He collapsed on to the stone tiles. James and Remus left him, whilst they grabbed some large, heavily spined books off the shelves, one labelled: The Book of Magic Spells: Step-by-Step Instructions for Enchantments, Charms, and Hexes

"Surely it can't be that difficult to do, and if we can't do it with the books then we can always ask my parents, we've got one 'round the-"

"What in Merlin's name are you doing, Mister Black?" Came the sharp, recognisable voice of McGonagall. She was stood over his limp form, one eyebrow raised in question.

"I...I'm dying Minnie, I can't-" he coughed for effect, "I- they dragged me here, its- it's killing me!" He raised his arms, holding his hand out to the sky. "I...I can see light. A...a tunnel! It's calling my name..." A second passed and his arm dropped and his eyes shut.

"Oh please, Mister Black. If you are planning on lying across the floor like an animal, I suggest you do it somewhere else, or at least not in the entrance, in the way." She stepped over his legs and headed down one of the aisles, and with a simple thought of Accio and a flick of her wand, multiple books came flying towards her outstretched hand. She walked back over to the door, and gave Sirius no attention as he exited the library.

"Hey Moony, I think we've actually killed him. We're gonna have to Leviosa him back. Or we levicorpus him... What do you think?"

Sirius shot up and dusted off his shirt. "No, no need for that, I'm alive."

"Thought so."

oo0O0oo

The next morning, Lily woke up to a loud crash and a puff of purple smoke seeping under the door. She tiredly dragged herself out of bed and opened the windows. Mary Macdonald in the bed opposite sat up and mumbled a sleepy "Wha's goin' on?"

"Don't worry 'bout it, probably jus' those stupid boys again, go back t'sleep Mary." Lily yawned, climbing back into her four-poster. Snoring followed shortly after.

Little did they know that the effects of the purple smoke would ruin their day.

oo0O0oo

"My hair! What the absolute-"

"My glasses are stained, I can't see, Rem!"

"Where are you James? I can't see a thing either-"

The very same purple smoke had first flooded the dorm of the Marauders. They were experimenting with potions in the centre of their room when James tripped over someone's dirty shirt on the floor, knocking a glass vial that Sirius thought would be safe to teeter on the cauldron into the potion, causing it to bubble and fizz rapidly. 

It was thicker than fog, therefore they couldn't see anything or each other. It had travelled under their door and down the stairs, into the common room and apparently up the stairs to the girl's dorms.

oo0O0oo

"What the bloody hell have you done to us? I'm purple for Merlin's sake! Reverse it now or so help me-"

"Calm down Evans, it will wear off."

"Eventually," Remus whispered under his breath.

The majority of Gryffindor (somehow it didn't reach the top half of the tower and only reached half of the girls) had assembled in the common room once the smoke had dissipated, and had come to realise they had been dyed a striking, vibrant shade of purple.

A couple first years had started to panic, however the rest of the house had been in similar situations caused by the troublesome boys. By now they had been changed into almost every colour of the rainbow.

"My hair! My beautiful luscious locks of hair! It's purple! What am I meant to do with this? This throws off my look entirely, it's going to clash with my jacket!" 

"Yeah, well all my uniform and even the walls are purple in my room, never mind your bloody hair, mate." Came an obnoxious third year, who was peeling off his purple socks, sighing at his purple feet.

Everyone seemed to freeze. Sirius stood up straight and Remus and James moved to stand behind him ready to hold him back from pummeling the boy to death.

"Ex-excuse me? Never mind? Never. Mind? I'll have you know, mate, that my hair is more precious than you and everything you own and love combined!"

The third year stepped back, and widened his eyes. "Alright mate, chill out, it's your own fault anyway." 

"I will bloody kill you in a minute" Sirius growled. 

"Hey! Stop it, one point from Gryffindor each," glared Lily, getting many looks of outrage from the others.

"Someone go to Professor McGonagall. She'll know how to fix this."