Imagine Remus
Having a perticularly bad full moon early in his first year. He happens to feel ‘well’ enough to go to dinner the next day, and when dessert rolls around he reaches for the last piece of chocolate cake for someone else to take it with out knowing he wants it.
To shy to say anything he just puts his hands in his lap and looks down crestfallen. Just as he gets up to go back to the dorms he hears something being put in his plate. He looks at it and sees half a pice if of the cake he wanted.
He looks across the table as he sees the persons arm move back to find it was Sirius who had give him half of his own cake. The other boy shrugged and gave Remus a smile not saying anything. Remus smiles back and starts a conversation as he eats it. The first one he’s really had during his time at Hogwarts so far.
Thats when he decided to be friends with him, that he was good people.