Tiberius's mother married Augustus

Augustus held the emperor's authority in 39 BCE but did not yet have the title. Attracted to Livia's beauty and the fact that she was carrying a second son at the time, Augustus divorced his wife, who was also expecting and forced the older Tiberius to give up Livia so that he could marry her. Livia left Nero and wed Augustus because she desired a stable existence for herself and her child. When Tiberius' younger brother Drusus was born a few months later, he was sent to live with his parents while Tiberius stayed with his father. Tiberius, who was nine years old at the time of his father's passing, moved in with Livia and the emperor with Drusus. The two boys learned together, played together, and took part in the required rituals of temple dedication and victory celebration, along with the emperor's daughter Julia, who was their age. Their cousin Marcellus, the son of Octavia, Augustus' sister, joined them.

All three sons received the appropriate training in the absence of clear legislation specifying who will succeed Augustus as emperor. They received training in eloquence, literature, diplomacy, and military prowess, and soon they also started participating in ceremonial state activities. Tiberius was the first to do so since he was the oldest. Tiberius, a 13-year-old, rode the right horse of Augustus' chariot in the triumphal procession after Augustus defeated Cleopatra and Antony at Actium. He was not a very attractive man, but he was well-behaved.