The greatest gift an artist could give another artist, taking them on the road and sharing their audience. Natalie Merchant did that for Tracy Chapman.  Fast Car would not have been added to the radio without power brokers seizing the opportunity that she was touring with Natalie merchant who at that moment was considered a bigger mainstream act. Made her career. John Lennon walking into RCA and telling the president to sign Harry Nilsson for one million dollars, same thing. RCA president later said (in the Harry Nilsson doc) he had no choice because it was John Lennon. Elvis Costello taking Ron Sexsmith on the road and promoting Ron to the media calling him his favourite. Arcade Fire having Final Fantasy open tours fifteen years ago. The weight of mensch.