Not much is known about Junior's past. It is suggested that he has a history as an information broker, keeping tabs on the various goings-on of Remnant. He is said to have a reputation for knowing everything and has business connections with underworld figures such as Roman Torchwick.
Yang Xiao Long arrived at the club and walked up to the bar to pressure Junior into saying what he knew about a woman she was trying to find. When he said he didn't know the woman, Yang began to leave, but Junior had his men surrounding her.
She feigned at kissing Junior then sucker-punched him to the other side of the club. After Yang defeated all his subordinates, Junior attacked again, but Yang activated her Semblance and knocked him out the window of the severely damaged club.
He tells them that Torchwick contracted his men to assist in Dust robberies, but Torchwick was apparently disappointed with his men's performance as he never heard from Torchwick or his men again.