Caligula was the son of Augustus’s granddaughter, Agrippina the Elder, and Germanicus, Tiberius’s nephew. Germanicus was extremely popular and had such a promising career as a general that Augustus made Tiberius adopt him as his son with the intention that Germanicus would succeed Tiberius in time. Suetonius explains how Caligula became known as “Caligula” rather than his birth name Gaius. The name is a diminutive form of caliga, which were soldiers’ boots—as a child, Gaius wore a miniature version of a soldier’s uniform. As he grew older and his mother and brothers were imprisoned and killed, Tiberius had Caligula live with him on Capri, where Caligula had to avoid being tricked into making treasonous comments against Tiberius.

Suetonius claims that Caligula had a vicious and decadent personality from the start. Allegedly Tiberius would remark “that he was rearing a viper for the Roman people” (Section 11). Caligula married Junia Claudilla. After she died in childbirth, Caligula had an affair with Ennia Naevia, the praetorian prefect Macro’s wife. With their support, he may have, according to one rumor, poisoned Tiberius and smothered him with a pillow.