Dio Brando is a vampire a mysterious past, along with Diego Brando, and is seemingly unrelated to the Dio of the JoJo Chrono. All that is for sure is that his father was George Joestar, and that he was a Top Law Student, shortly becoming and ace prosecutor in the town of Rougeport. Dio sees the town as a hive of scum and villainy to be cleansed. He eventually meets his partner and relative Diego Brando, and they join forces, hoping to claim whatever is beyond the thousand-year door for themselves.
Not much of Dio's past is known, other than that he was a son to George Joestar, and that he became a vampire somewhat recently, as he was still discovering new powers throughout the Paper Mario Chrono. He was also a Top Law Student, a fact he enjoyed boasting about. Soon after he became an ace prosecutor with a reputation for never losing as well as his insistence that his accused by executed.