Diavolo is the boss of Passione, and the father of Trish, intending to kill her to keep his existence a secret, targeting Giorno's group after they refused to hand Trish over. Diavolo uses the incredibly powerful Stand, King Crimson, which has the power to partially affect the causality of the near future in relation to himself; allowing him to negate processes, leaving only their consequences. Activating its power causes a time skip, where everything except Diavolo and King Crimson is changed to be in the state they would have been a few seconds later; for example, a bullet that would have hit Diavolo will suddenly be shifted to be on his other side. Diavolo is able to predict what will happen during the timeskip by using King Crimson's second face, Epitaph; this sub-power can also be used by Doppio to see seconds into the future.

Diavolo is a secretive, violent, and determined man who wants to erase any information about himself. His voice is in the low range.