Darius is an Urb residing in Miniopolis in the DS and GBA versions and Urbzville in the console version. The GBA and DS version shows him as the leader of the Streeties. He has the highest rep out of anyone in the game (his face is seen on billboards, which reveals that he is famous on a citywide, or even national level). He trains the console version protagonist (normally Jayde) to replace him when he retires to his blimp, making her arguably about as famous as he was. When this happens, he hands the player a key (on a gold chain around his neck) to his ultra-luxury penthouse. His source of wealth is unknown, but is sometimes shown to be the result of gangster-like practices (in the console version he has a counterfeit press, and in the GBA and DS versions, he is paid by Daddy Bigbucks to assault and intimidate the player).
He has contacts with will.i.am and with the same player, but you cannot interact with him (although there is a rare exception during the party of midnight in the V.I.P area, where you receive a bonus from him to drive off renters).
Although he retires in the Console version, he will still appear in districts at Midnight. He will also keep in contact with the player regularly. Usually to give them advice or to scold them for wearing the wrong style of clothing for that district. He still speaks as if he owns the city even after retiring.