Who he seems to be
A white rabbit-like creature โ black slit eyes, a mustache, a brown hat, plaid brown pants. He's unfailingly polite, calls the player "friend," and makes a string of small, harmless-sounding requests across five visits: coffee, a briefcase to hold, a photograph, and finally, a place to hide.
The game's own scanner reads him as green โ not an anomalyโ the entire time. That's the whole point of him.