My Own Private Idaho (1991)

Mike Waters lives on the street and befriends the somewhat older and streetwise Scott Favor who shows him what is necessary to survive. Waters suffers from narcolepsy and can fall asleep at any moment and in almost any circumstance. Favor comes from a rich family and is rebelling against his own background.

They travel together extensively - Waters is driven by the need to find his biological mother - and spend time in Italy. Later in life however, Favor has joined mainstream society and has little time for his old friend.