Publius Septimius Geta was born in AD 189 in Rome, as the younger son of Septimius Severus and Julia Domna.
He most the likely possessed the same bad temper as his infamous brother Caracalla. Although it appears he was not as brutish. This difference was only enhanced by the fact that Geta suffered from a slight stammer. In his time, he became quite literate, surrounding himself with intellectuals and writers. Geta showed his father much more respect than Caracalla and also was a far more loving child to his mother. He took great care about his appearance, liking to wear expensive, elegant clothes.
Caracalla was declared Caesar already in AD 195 (to provoke Clodius Albinus into war) by Severus. Geta's elevation to Caesar took place in AD 198, in the same year in which Caracalla should be made Augustus.
And so it appears quite obvious that Caracalla was being groomed as the heir to the throne. Geta was at best a substitute, should anything happen to his older brother.
During AD 199 to 202 Geta travelled through the Danubian provinces of Pannonia, Moesia and Thrace.
In AD 203-4 he visited his ancestral north Africa with his father and brother.
In AD 208 Caracalla and Geta left for Britain with their father, to campaign in Caledonia. With his father ill, much of the command lay with Caracalla.
What made Severus grant his second son the title of Augustus is not quite clear. There were wild rumours about Caracalla even trying to kill his father, but they are almost certainly untrue. But it might have been that Caracalla's desire to see his sick father dead, so that he could finally rule, angered his father. But what also might have been the case is that Severus realized he had not much time to live, and that he rightly feared for the life of Geta if Caracalla came to power alone.
Septimius Severus died in February AD 211 at Eburacum (York). On his deathbed he famously advised his two sons to get on with each other and to pay the soldiers well, and not to care about anyone else.
With the Caledonian campaign at an end the two then headed back for Rome with the ashes of their father. The voyage back home is noteworthy, as neither would even sit at the same table with the other for fear of poisoning.
Back in the capital, they tried to live alongside each other in the imperial palace. Yet so determined were they in their hostility, that they divided the palace in two halves with separate entrances. The
doors which might have connected the two halves were blocked.
Each brother sought to gain the favour of the senate. Either one sought to see his own favourite appointed to any official office which might become available. They also intervened in court cases in order to help their supporters. Even at the circus games, they publicly backed different factions.
Their bodyguards in a constant state of alert, both living in everlasting fear of being poisoned, Caracalla and Geta came to the conclusion that their only way of living as joint emperors was to divide the empire. Geta would take the east, establishing his capital at Antioch or Alexandria, and Caracalla would remain in Rome.
The scheme might have worked. But Julia Domna used her significant power to block it. It is possible that she feared, if they separated, she could no longer keep an eye on them. Most likely though she realized, that this proposal would lead to outright civil war between east and west.
A plan was uncovered that Caracalla intended to have Geta assassinated during the festival of Saturnalia in December AD 211. This led Geta to only further increase his bodyguard.
Alas, in late December AD 211 he pretended to seek to reconcile with his brother and so suggested a meeting in the apartment of Julia Domna. Then as Geta arrived unarmed and unguarded, several centurions of Caracalla's guard broke through the door and cut him down. Geta died in his mother's arms.
What, other than hate, drove Caracalla to the murder is unknown. Known as an angry, impatient character, he perhaps simply lost patience. On the other hand, Geta was the more literate of the two, often surrounded by writers and intellects. It is therefore well likely that Geta was making more of an impact with senators than his tempestuous brother. Perhaps even more dangerous to Caracalla, Geta was showing a striking facial similarity to his father Severus. Had Severus been very popular with the military, Geta's star might have been on the rise with them, as the generals believed to detect their old commander in him.