clarification on all mechanics is in a comment in the background element inside the project companion registry run here JUST ONE THING. these are not called pets very explicitly because I think the words pets v. companions have very different meanings. Companions imply an equal sense of understanding and respect whereas a pet does not imply that. These animals cannot speak with you, but they do have a level of intelligence similar to the cats. You must earn their trust to earn their favor. One cat may have 2 small companions OR 1 large companion throughout their lifetime. Once you claim a companion you cannot get rid of it, so choose wisely.
all art by me except for the inside joke gag lol which is an image from google