Who is Ben from Stone Butch Blues and what is their importance?

Ben is a man who rides with Jess on a temp worker bus. He has a history with a few dark paths, including time in prison. Ironically, Jess cannot open up with this man who is opening as few men do because of her greatest secret: She's not the man that Ben thinks she is. Her experience with Ben shows how taking the hormones has further alienated her from people, even people who don't know her from before.