Treacle Jr. (2010)

A middle aged man, Tom, walks out one day on his wife and baby boy and his seemingly happy life with no explanation. He opts to live on the streets of London. Alone in a park at night he is set upon by a gang of violent thugs, in his bid to escape he accidentally runs into a tree. In A&E Tom meets an extremely happy, fast-talking individual, Aidan, the complete opposite of Tom. Too polite, or too weak to ask him to leave him alone Tom tries to get away from him but to no avail, Aidan sticks to Tom like glue. Tom reluctantly becomes involved in Aidan's life and he quickly realizes that this child like man clearly has his own problems, except Aidan can't see them, his shiny optimism blinds him at every turn, even from his 'girlfriend' the dangerous and volatile Linda.

Unfortunately the movie Treacle Jr. is not yet available on HBO Max.