Nero's origin remains unknown. He was raised in the city of Fortuna as an orphan and is later taken in by Kyrie's and Credo's family.
He often acts sarcastic, rebellious and rather antisocial, as he likes going alone on special missions and shows an adverse attitude towards the ceremony of the Order of the Sword, even though he is one of their Holy Knights. The Order worships Sparda and wants to protect the world from demons.
Nero falls in love with Kyrie some time prior to the events of the game, and this love plays a crucial part in the plot.
Nero wields the weapons Blue Rose, Red Queen, and Devil Bringer. He later receives Yamato, a sword that once belonged to Dante's brother, Vergil.
As he wants to give Yamato to Dante, the latter tells him to keep it, as it "stays in the family". This remark cemented the theory that Nero is actually an incarnation of Vergil, but this has never been officially confirmed. Instead, it was hinted in the DMC 4 novel that Nero is Vergil's son.