Wash and Maine as bros, from reeberry
He’s not really sure how it happened — the cat was a stray, brought in by somebody (York, probably, with that bleeding heart of his) and left in the common room, and someone had to feed it, Wash said, if no one was going to get rid of it (doesn’t anyone else care about regulations, honestly) and he’d done it all himself until he realized that the milk in its bowl came from Maine stealing it out of the mess.