This is a bit different from my usual style - an experiment, I suppose - so I'm not too sure what it's like. I think I quite like it, though.
Friendship seemed to come so easily to other people, Peter thought; like mixing together two colours of paint to create something different, something which, though clearly the product of those two colours, was altogether prettier than they had been alone. That Snape boy was completely awful by himself, yet when his dull green was mixed with Lily Evans's bright yellow, a light lime green was produced: a sharp, eye-catching colour which was not so bright as to be unpleasant. Their friendship, too, was clearly unexpected – Gryffindors and Slytherins, after all, didn't interact on principle – though something about it seemed to make sense.
James Potter and Sirius Black, too, were just colours mixed together on a paint palette. James, a vibrant Gryffindor red, full of fire and brilliance and the sort of bravery that comes from not thinking; Sirius, orange, rebellion and brightness and a scream of 'I'm different!': together a lighter red, a darker orange, a strange mixture of the two which inspired images of a flickering flame, something burning and somehow dangerous; yet comforting, warm, even friendly.
Peter had been watching these others jealously, wishing for someone to share his own blank, clean white with. He wondered how it would look with Remus Lupin's yellow (friendly, helpful, open): would it be merely a lighter shade of Remus's own colour, or would it turn more of a mediocre cream? Perhaps, when he'd befriended Remus, the pair of them could join up with James and Sirius to create something bigger than a mere mixing of colours – the four of them could be a painting; whites and reds and oranges and yellows streaked across an easel in a raging inferno. Peter wasn't sure whether it would be a pretty, warming bonfire or a destructive forest fire; but he thought that he could only find out by letting it burn.