Remus awoke amongst the Hogwarts house ghosts. He'd known them from his days as a student and a teacher.
"Good Evening!" said Sir Nicholas. "Welcome to the Gathering of Ghosts. We have met tonight to welcome you to the ranks."
"The ranks! Oh my Merlin I've died then. Poor Sirius.. he'll be so devastated." said Remus with tearful eyes.
"Actually you'll be happy to know he's already here." replied the Grey Lady gently.
"Oh my you're kidding?" said Remus mouth agape.
"No Remus, he's been waiting for you." Helena assured him.
"Firs' tings firs' ye gotta 'ear the rules!" said the Bloody Baron.
"Yes as I was saying" interrupted Sir Nicholas "You must stay on the school grounds during the school year and you were in Gryffindor so you can mostly help me. Don't think that limits you though! You can go all about the castle and interact with amy student, staff, or otherwise. That's the special pardon you get for sacrificing yourself for this school. No limits!"
Remus thanked all of them and rushed out to find Sirius. He found he must have been in the dungeons aside from the damp smell, he could see the entrance to the Slytherin common room. There's no way he'd find Sirius down here he thought and began to head to higher ground.
He was in the entrance hall when he ran into Peeves. He was going to really mess with Remus, so he hid in a suit of armour. With his voice disguised as Sirius' he called to Remus,
"There you are you git!"
"Merlin's beard there you are! I thought I'd lost you forever!" He ran towards the suit of armor and when he flipped up the lid Peeves sprang out and mooned him. "HA HA MOON-EE I GOT YA, YA BIG BUTT LOSER!" he taunted.
At that moment Remus was filled with rage and something crazy happened. He morphed into his werewolf form. Once he realized what happened he immediately made a run at Peeves. He didn't know what would happen but he was already dead and this poltergeist had it coming. Peeves could not get away fast enough, in was seemed like a flash Remus had his paws on him. He pinned him down and with rage in his eyes and his terrifying animal appearance it was obvious Peeves was shook to his core.
"Don't you ever fuck with me again! Or I'll figure out how to kill you!" said Remus in an unfamiliar voice.
"Y-Y-Y-YES SIR... never again sir." Peeves whimpered. Remus released him and felt himself change back to himself. He thought about how this ghost thing might not be so bad, while he continued to walk the castle looking for Sirius, especially if he has control of his transformations. He figured he would just go for the obvious and head to the Gryffindor common room. When he got there he went to their old sleeping room. The familiar four posters where still there as well as a familiar floating figure.
Sirius was sprawled out on his old bed with a come hither look.
"I thought you'd never find me" said Sirius as cool as could be.
"I had to figure out this ghost thing and then I literally floated right up here. So stop teasing me." Remus replied.
"I would have come down to greet you but I had a run in with Peeves and that guy is THE WORST. Was he always that horrific when we were here?" asked Sirius.
"Something tells me we won't be worrying about him anymore." smiled Remus.