Miltia is a member of Junior's Club. As she is commonly by Junior's side, it is possible she is a higher-ranking member or even a bodyguard.
Melanie is a member of Junior's Club. As she is commonly by Junior's side, it is possible she is a higher-ranking member or even a bodyguard.
Not much is known about Roman's relationship with Junior, except that they are business partners in some way. This is demonstrated by Roman's brief appearance in the "Yellow" Trailer, discussing an unknown subject with Junior. Later on in "Ruby Rose", some of Junior's henchmen are seen under Roman's command in order to assist him in robbing the Dust shop From Dust Till Dawn.
After they are defeated, Roman claims they were "worth every cent", suggesting he hired them from Junior. This was later confirmed by Junior himself when Yang questions him. They have since ceased contact with one another, likely due to Roman's disappointment with his men's performance.
Yang's acquaintance with Junior is short but eventful. Yang originally approaches him for information, even hurting Junior slightly in the process to get an honest answer. Even after this, when Yang offers to kiss and make up (literally), he isn't above accepting the offer. When he is knocked out, he has small hearts circling his head, implying he's at least somewhat attracted to her.
Later, Yang is responsible for damages to Junior's dance club and the assault on Junior and his associates. When Yang later returns to question Junior about his ties to Roman he is shown to be visibly nervous and intimidated by her presence, likely owing to their previous encounter.
Junior only crossed paths with Neptune once, when Yang brought him with her the night she returned to his club. He ignored Neptune initially, then seemed largely unimpressed with him, calling his question stupid and asking Yang who he was.