Born Publius Septimius Geta in AD 189 in Rome, Geta was the younger son of Septimius Severus and Julia Domna. Geta’s elevation to Caesar took place in AD 198, in the same year that Caracalla was made Augustus. It appears that Caracalla was being groomed as the heir to the throne, and Geta was at best a substitute, should anything happen to his older brother. This undoubtedly contributed to the rivalry that existed between the two brothers.
The rivalry was so fierce at one point that Septimius had both living with him to prevent one doing violence to the other. Septimius’ plan failed and on his deathfbed in february AD 211 he was still attempting to arbitrate between them. He gave his, now, historical advice,
“get on with each other, pay the soldiers well, and don’t care about anyone else.”
His death left the boys’ mother to try and manage to keep peace between them. Only partically successful, Julia’s main worry was for Geta, and time proved the worry warranted. Although murderous attempts were reciprocal, Caracalla proved the most adept, and Geta’s joint rule of the Roman Empire ended in December of AD 211.