Feed the little buggar I say but don't assume the cat is now your cat or wants to be your cat or is going to be nice, or is going to let you stroke her/him. Poor little creature is dependent on humans anyway; alternative is hunting down birds etc. (or killing rats and mice but they are usually already carrying poison). I feed feral/lost whatever cats as the mood takes me and I enjoy that we eyeball, have a bit of a chat, and then off they go. Maybe they/it will turn up again, maybe not, but at least that feed was nice. And yes, they're all Pepe Le Phew - that's cats for you.