Authors note: I am aware that Pettigrew was a big part of the mauraders era but I do not like him so for the most part I'm not going to mention him.
Update: Added a second part that I forgot to include earlier
A boy who was barely 11 sat next to the window in an empty compartment, watching the people on the platform disappear behind them as he headed to hogwarts school of witchcraft and wizardry for the first time.
Sighing he ran his fingers through messy black hair before looking up as he heard a knock on the door. It opened and two boys who looked to be the same age as him peeked inside. "Everywhere else is full." one of them said, he had long black hair that fell to his shoulders. "Can we sit here?"
The first boy shrugged. "Sure." He said before looking back out the window. He could hear the others getting settled and putting their things away before they sat down.
"My name is Sirius Black." He heard one of them say, turning around the boy with long hair had his hand out stretched.
He took the boys hand and shook it before saying his own name. "James Potter."
He looked to the other boy. "Remus Lupin." He told him, Remus had tidy brown hair, was a little taller than both of them and looked as if he had been recently very sick.
Not sure what to talk about the 3 boys remained silent for a while and Remus soon fell asleep. "What house are you hoping to be in?" Sirius asked him.
"I want to be in gryffindor, how about you?"
The boy shrugged and put his feet on the seat across from him. "Anything but slytherin, that's what the rest of my family has been in." He said.
Hearing this got James' attention. "Why don't you want to be in the same house as them?" He asked him.
"I don't want to be like any of them."
"Why not?" He asked curiously.
Sirius looked away from the other, he hated his family and was hoping that school would be his chance to get away from them. "Because I'm not like any of them." He answered plainly.
Getting a sense that the other didn't want to talk about it he nodded and stopped questioning it, turning back towards the window for a moment as he thought. Giving Sirius a smile James spoke once more. "Maybe we'll both be in Gryffindor."
Sirius looked back at him and returned the smile with a small one of his own. "That would be nice." He said as they arrived.
They woke up Remus and the 3 of them headed with the other first years and were taken across the lake to the school where they lined up before following the teacher into the great hall. The first years were sorted in alphabetical order and much to their surprise Remus, James and Sirius were all sorted into Gryffindor.
"Looks like we'll be getting to know each other quite well." James said as he sat between them at the table.
During the feast all three of them talked and could already tell that they would be friends for a long time. Just as it ended James caught the eyes of a young girl who he recognized as being sorted before him but could not remember her name.
Afterwards they were taken up to the dorm. "How about we have some fun before bed?" James suggested.
James took what seemed like a regular cloak out of his trunk, but upon wrapping it around himself his body disappeared, leaving only a floating head.
Sirius stood and circled the other, never having seen one before. "That is so cool!" He exclaimed.
"Thanks, my dad gave it to me." He explained before removing it. "I bet that all of us could fit under here." He said as he held the cloak up before smirking slightly. "How about we go exploring?"
Sirius and Remus looked at each other. "I don't think that would be such a good idea, especially so soon." The latter was the first to speak up.
Sirius looked between the two as if pondering the idea before smiling. "I think it would be fun, we need to find our way around sooner or later." He said with a slight shrug.
"That's the spirit." James said, clapping the other on the back before looking to Remus. "What do you say?"
"I still say it's a dumb idea." He said before sighing. "But I guess I'm in too, someone needs to keep you two from getting into trouble before the term even starts."
James smiled. "Alright, lets see how we all fit." He said as he draped the cloak over them before looking around. "Perfect, let's get going."
The boys grabbed a lantern as they left the dorm and began wandering the halls. "This place is huge, someone should make a map of it." James said before seeing Sirius smiling beside him. "What is it?"
"We could be the ones to make the map."
"That's crazy, it could take years to map out the entire building."
"And? We're here for the next 7, what is there to lose if we at least tried?" Sirius continued. "Think about it, there must be tons of secret passages, and probably even places the teachers don't know about."
James smiled. "Sounds like fun, I'm in."
Remus sighed once more. "I have to agree, the idea does sound interesting." He said, giving them a slight smile. "So I guess I'm in too."