In his youth, Volumnius became a good friend of Marcus Junius Brutus, who was a fellow student of philosophy. Like his friend, Volumnius joined the Hidden Ones and he followed Brutus in the conspiracy to kill Gaius Julius Caesar in 44 BCE.
With Caesar's death, Volumnius accompanied Brutus on his fateful campaign to the East, which culminated in Brutus' suicide after his defeat by the Triumvirs, Octavian, Marcus Antonius and Lepidus in the Second Battle of Philippi in 42 BCE.
Distraught over Brutus's death, Volumnius was one of the Hidden Ones who gathered in Philippi, Macedonia, and tried to use a Shroud of Eden to resurrect him. However, the Shroud was not capable of such restoration, and though Brutus opened his eyes and moved, he did not appear to breathe, and eventually fell still in a seeming second death.