Doppio is The Boss' younger, more innocent and eccentric underboss. As a member of Passione, he thinks of himself as the most loyal subordinate to Diavolo, but in reality, the two are separate souls inhabiting the same body.
During the course of Vento Aureo, he helps Diavolo to act and move around undetected. It is ambiguous whether Doppio is truly a Stand User, but he is able to partly wield King Crimson in battle.
