Qui-Gon Jinn is a good character, but a lame Jedi:

got killed by a Sith
his inofficial apprentice becomes Vader
his former Master became Sidous apprentice

Something got wrong with Jinn, and it is actually said in TPM, as if he was a member of a third order, not with the dark side, not completely with the light, between. He tries to set things right by helping Yoda and Ben how to live through the Force but the harm was done. Could be fun to see his force ghost in Ep VIII, along with Hayden’s.