Tiberius Claudius Nero was born in November 42BC, during the civil wars, to Tiberius Claudius Nero and Livia Drusilla. For the first two years of his life his parents were living in exile. In 38BC, at Octavian’s request, the pregnant Livia divorced Tiberius’ father and married the upcoming Octavian.

Tiberius’s early life was uneventful. He appears in 32BC giving his father's eulogy and in 29BC both he and his brother Drusus rode along with Octavian in his triple celebrations upon returning to Rome in 29BC. Augustus started grooming Tiberius and Drusus for imperial careers from an early age, they were advanced rapidly with both being granted the right to serve as Praetor and Consul five years before the minimum required age. Tacitus suggests that Augustus preferred Drusus to Tiberius but there is no evidence that this was true and Augustus was careful to advance the boys equally in line with their three years age difference

As Tiberius aged Augustus started to groom him as a general, he went with Augustus on his Spanish campaigns in 23BC and was in 20BC was sent to the East, under the guidance of Agrippa, to ensure the return of the standards lost under Crassus. Years of negotiation had failed to secure their return and so Tiberius led a large army into Armenia resulting in Parthia quickly agreeing to return the standards, this was one of Augustus proudest successes. Tiberius returned to Rome in 19BC and married Agrippa's (Augustus's heir at that time) daughter Vipsania. He then was sent to help Drusus in the west and Tiberius was chiefly responsible for the pacification of Raetia between 16-14BC. In recognition of his achievements and to gain prestige in 13BC Tiberius returned to Rome to hold the consulship.

Julia

Agrippa's death in 12BC left Augustus without a successor and it is commonly thought that Tiberius was marked as successor from this point as he was forced to divorce his beloved Vipsania and marry the recently widowed Julia (Agrippa's wife and Augustus's daughter) in 11BC. It is likely however that both Tiberius and Drusus were intended as successors, Augustus just saw no need to change Drusus's marriage as he was already married to Augustus’s niece Antonia. After Agrippa's death Augustus used both Drusus and Tiberius as his main generals in his campaigns. Tiberius led the campaign in Pannonia (taking over Agrippa's command) and Drusus was on the Rhine. However, in 9BC, Drusus fell from his horse while campaigning nd died from the injuries. After Drusus’s death Tiberius was transferred to the Rhine. Significantly Tiberius was allowed to command these armies on his own authority, rather then as a legate of Augustus, presumably to allow him to earn a triumph and to further increase his prestige. Tiberius campaigning on the Rhine was successfully enough that by 8BC he was awarded a triumph and made consul designate for 7BC. This triumph was more ceremonial then anything else as no great results had been made in Germany and served as recognition for Tiberius’s services while raising his profile in Rome.

Tiberius's marriage to Julia was presumably cordial at first and Julia had a son, probably in 10BC, who died shortly after birth. Their marriage deteriorated badly however and was the source of much unhappiness for Tiberius while Julia became famous for her infidelity. By the time of Tiberius's consulship in 7BC, Julia's eldest sons, Gaius and Lucius were starting to make a number of public appearances in Rome, as was appropriate with their ages, and the people had become accustomed to seeing them. In 6BC the people showed their support of Gaius by electing him as consul, even though he was only 14 years old and had just taken his toga virilis and legally become a man. Augustus was, or at least pretended to be, very angry by this election and deferred the consulship to AD1 when Gaius would be 21. Tiberius would have been very aware of the boys growing prominence, especially as Julia would have been promoting their causes.

A Young Tiberius

In 6BC Tiberius was granted tribunicia potestas for five years and given imperium over the East when he suddenly announced a desire to withdraw and retired to Rhodes. This is no clear indication why Tiberius did this and there is vast speculation of the reasons behind it. It is usually considered as a self imposed banishment but may have been the result of the breakdown of his marriage with Julia and the arising jealousies as Julia promoted her sons and Tiberius wanting to avoid conflict with Gaius and Lucius. It has been suggested that Augustus may have sent Augustus as a agent in the East as provincial governors frequently visited him and Tiberius’s return to Rome coincided with the peace settlement with Parthia in AD2. Though Augustus's claims that Tiberius had deserted him when Tiberius left for Rhodes and Tiberius’s tribunician powers were not renewed when the expired in 1BC suggest this might not be true.

Although Tiberius had returned to Rome in AD2 he was clearly on the outer with Augustus as he was not given a political office on his return or in AD3 or AD4. Fortune changed in his favour however as Gaius died in AD4 and Augustus was left without a successor. After a period of negotiation, in June of AD4, Augustus adopted Tiberius and obtained a 10 year grant of tribunician power for him as well as a grant of imperium for the provinces. Augustus also adopted Agrippa and Julia’s final son, Agrippa Postumus (he was born after Agrippa died) and made Tiberius adopt Germanicus, his brother Drusus's son, who had blood of Augustus’ family through his grandmother Octavia (Tiberius had a son Drusus himself who was slightly younger then Germanicus). It is thought Augustus was creating another two tier system of brothers with the immediate successors of Agrippa Postumus and Tiberius and then next generation of Germanicus and Drusus. Agrippa Postumus however did not have the same character as his brothers and by AD7 Augustus disinherited him and exiled him to a desert island, leaving Tiberius as his only realistic heir.

The first act after the death of Augustus was the execution of Agrippa Postumus, the historians are confused who was responsible but Robin Seager found an attractive possible scenario. Under Roman law if Agrippa was alive at the time of Augustus’s will being read he would have to be explicitly disinherited, but he was not mentioned in the will. This meant that Augustus knew Agrippa would be dead by the time his will was read. This certainly implicates Augustus, who would have wanted to remove any possible complications for Tiberius accession, but who else was involved remains unknown.

Whoever was responsible it was a sensible move as Postumus is universally called brutal and uncivilised in the sources and he had been exiled by Augustus in AD7. If he had been allowed to live he would become a pawn for ambitious men, or those who disliked Tiberius and he would have been the cause of political instability. It was at this time that Tiberius cut off the funds that supported his former wife, and Augustus’ daughter, Julia in her exile at Rhegium. Julia soon died of starvation; this was probably done for very similar reasons to those behind the death of Agrippa Postumus. An example of the rallying power of Agrippa Postumus comes from Tacitus, who records that Agrippa Postumus’s servant Clemens travelled around Italy pretending to be Agrippa Postumus. Tiberius captured Clemens and had quietly executed and he excused all of Clemens’ supporters as they contained key members of the Praetorian Guard and upper classes, reflecting just how powerful Agrippa’s support was.