Housecat Roommate

A roommate who comes and goes with no heads up or warning. Oftentimes, they disappear in the middle of day and don't return until late at night. They also leave alcohol at the door, in similar fashion to a cat with dead animals.

My bro is such a Housecat Roommate. H literally vanished at noon yesterday, and he got back at two in the morning. Where does he go?