James: You both met just before the sorting ceremony when he was talking about how Gryffindor is the best house but you politely told him that every house was special and it wasn't bad if you were put into a specific one.

Sirius:  You met at one of the pureblood parties that was thrown at someones mansion in an attempt to organise betrothals and connect with other purebloods. Sirius wasn't interested in anything, choosing to sit at the back of the room and you eventually joined him. You both ended up bonding over the stupid views of your families which led to you becoming friends.

Remus: You had been looking through the books at Flourish and Blotts when you bumped into someone. That someone was him and you both apologised profusely. You offered to pay for the books that had fallen when you had collided but he politely refused so you then asked if he wanted to go to Florean Fortescue's Ice Cream Parlour to make up for it. He accepted and you two paid for your books before going to the Ice Cream Parlour.

Peter: You two met on a Hogsmeade trip when you both reached for the same sweets and he ended up letting you take it. You both talked to each other all the way back to the castle.

Regulus: You met in Potions class when Slughorn paired you two together to work on potions for the rest of the years. He hated you at first but as the time went on, he began to like you more because of your kind spirit, sense of humour and ability to make exceptional potions.

Lily: You two met when she was looking for a compartment to sit in, coming across yours. She introduced herself and sat down with you because you were alone.

Marlene: She was annoying some Slytherins on the train when she saw you, deciding that she liked you so she stopped and offered for you to sit with her. You refused, wanting to stay with your friends. All throughout the next year, she kept an eye out for you and made sure you were doing okay.