Diavolo is the main antagonist in JoJo's Bizarre Adventure: Vento Aureo.
As the discoverer of the Arrows, Diavolo is responsible for the proliferation of Stand Users in the world. Living an extremely secretive life as a nonperson, he is the "Boss" of the gang Passione, which corrupts Naples by dealing drugs in the streets, making him Giorno Giovanna and Bruno Buccellati's superior and greatest enemy. Diavolo is also the father of Trish Una , and commands Bucciarati's Gang to bring her to him whilst keeping her safe from the traitorous Squadra Esecuzioni.
Diavolo is secretly the alternate personality of Vinegar Doppio and is a Stand User who wields the incredibly powerful King Crimson.
Much of Diavolo's origins and past are left in mystery. He was supernaturally born in an all-female prison in Italy in the summer of 1967 to a two -ear pregnancy, with no possible subjects for a father within the prison. As his mother still had several years left in prison, Diavolo was adopted by a priest and moved to Sardinia, where he would grow up.
When Diavolo was 17-19 years old, he met and had a relationship with a girl named Donatella Una. He presented himself to her as "Solido Naso", showing an obsession with erasing his past and identity even before he was the boss of Passione. Diavolo unknowingly had a daughter with Donatella, named Trish Una.
One day, the priest who raised him found Diavolo's mother mysteriously hidden underneath the floor with her mouth and eyes sewn shut. Later, a fire would start and kill several people with the priest and Diavolo himself listed as deaths. Diavolo is shown to have directly killed the priest himself in the anime. It is implied Diavolo started the fire himself to fake his death.
Diavolo would then, for reasons unknown, join an excavation in Egypt. He would there discover a box with six arrows, which intrigued him due to the power they gave off to him. He would take the arrows to a witch named Enya Geil and sold five of the six arrows to her. Enya would later introduce the arrows to people such as DIO and [[Yoshihiro Kira], which would cause the spread and increase of Stand users around the world.
Diavolo would then found Passione and use his remaining arrow to create Stand users within his own organization, most likely creating his own Stand King Crimson with the arrow as well.