Who is Jan Meadows from Factotum and what is their importance?

Jan becomes Henry Chinaski's most steady girlfriend in Los Angeles, on the rebound from Laura. They move in together three days after meeting in a bar. Jan's meanness and hostility excite Henry sexually. She is hot in the morning when hung-over, while Henry likes sex at night. She can be playful in bed, making a little paper hat for Henry's penis before devouring him. They spend a lot of time at the racetrack and otherwise do little but drink wine, make love, and steal cigarettes from parked cars during evening walks. When Henry and Manny begin making money at the track, Jan mocks Henry as "Mr. Big Horseplayer" and demands sex. Their arguments are always the same: bums are greater lovers than clock-punchers.