Likely born in March of 189 AD Publius Septimus Geta is the son of Septimus Severus and Julia Domna. Geta was advanced to the rank of Caesar in early 198- at the same time his older brother (Caracalla) was advanced to the rank of Augustus, it would be another 10 years before Geta achieved the rank of Augustus. This may have contributed to the competition and dislike between the two brothers. This bad blood between the two grew into outright hatred. Geta was finally advanced to the rank of Augustus in 209 AD, thereby creating three emperors for the first time in Roman history. The rule of three emperors ended in soon with the death of Severus in 211 AD. The two brothers ruled and lived with suspicion and hatred of each other. Their rivalry was resolved less than a year later when Caracalla invited Geta to a meeting to resolve their differences and Geta was killed by guards loyal to Caracalla.
A point to note: On Geta’s earliest coinage his first or personal name id used as Lucius (198- 199 AD) and then changed to Publius thereafter. There is no historical note or information for why this may have been done.
Of interest is that his later coinage bears out the similarity in appearance of he and his father.