Harry:
After you had caught Harry in the 'Restricted' section of the library when you guys first met, he asked if you could hang out with him at Hogsmeade.
During your time at 'The Three Broomsticks', you guys bonded quickly.
Ron:
You were at Hagrid's hut after you bumped into the red headed boy and all of a sudden, the boy came back asking for his Potions book that he had left.
After Hagrid gave him back the book, he insisted that Ron could stay for a bit. You and Rom began talking back and forth about recent news from the Daily Prophet.
Draco:
After Transfiguration class, you had a free hour. Draco insisted that he'd walk you to the Black Lake, after you said you were planning to just chill there.
When he walked you there, he sat down next to you and tried to strike up some conversations.
George:
After the feast in the Great Hall, George had followed you into the Gryffindor Common Room, and started to tell you jokes and tried to create a conversation.
Fred:
After you caught him with a prank, you and him had Defense Against The Dark Arts next, and he was talking to you on the way there.
Neville:
After Neville fell in front of you during Herbology, you helped him right back up as he sat next to you the entire time, trying to strike up a conversation about the class.