His father, who died in AD 21, was a grandnephew of the historian Gaius Sallustius Crispus (Sallust), who had no children of his own, and therefore adopted his sister's grandson as his heir.
He made his first speech in the senate during the reign of Tiberius, whom he addressed politely, and whose favour he won, although Suetonius maintains that the emperor's praise was insincere.
[1] Passienus was consul for the first time in AD 27, being named suffectus from the Kalends of July, as the colleague of Publius Cornelius Lentulus, and serving out the remainder of the year.
[6] Passienus married Domitia the following year, and became the stepfather of Quintus Haterius Antoninus, who would become consul under Claudius in AD 53.
[8] Shortly after his accession in 41, the emperor Claudius asked Passienus to divorce his wife, and marry Agrippina, for her husband Domitius Ahenobarbus had recently died.
[9] She herself had been exiled by Caligula in AD 39, due to her supposed involvement in a plot against the emperor, with her brother-in-law and alleged paramour, Marcus Aemilius Lepidus.
He was persuaded by Agrippina to name her as his heir; this proved to be his undoing, for he died by his wife's treachery, probably poisoned, about AD 47.