25 Days of Supporting Characters: 17
#17 J'onn Jonzz
Basically the opposite of Jon Carter. J'onn acted as the field leader to JLI and a sort of parental figure to most of the league.
Why he's important to Booster: Although his role in Boosters' life isn't as well defined as some he's the authority figure that can't quite believe the kids are all grown up and able to make choice of their own. He's also expressed this with Ted as well when he cruelly dismissed him in CTIC. As a result J'onn seems to feel too guilty about his behavior to confront Booster, something he feels he should have done (52.)
Suggested Reading: Booster Gold #25 Vol. 1 Where J'onn is one of the few people to know about Boosters' importance although he believes that Booster should never learn this. Reading this issue one has to wonder if hearing this bit of information is the only reason he accepted Booster back into the league. Nevertheless it's a nice hint to think still to come. Plus you can't hate an issue that has him using his cape as a pocket to store Boosters' costume in.