Born in Rome, and named after his father's benefactor,[2] Iullus and his elder brother had a disruptive childhood.
His mother Fulvia gained many enemies including Octavian (nephew and adopted son of Julius Caesar).
The army occupied Rome for a short time, but eventually retreated to Perusia (modern Perugia).
In the same year of Fulvia's death, Antonius' father Mark Antony married Octavian's full sister, Octavia Minor.
While Iullus' elder brother Antyllus and his stepbrother Caesarion were murdered by Octavian, he showed some mercy to their half-siblings Alexander Helios, Cleopatra Selene II and Ptolemy Philadelphus.
[4][5] Horace refers to him in a poem, speaking of an occasion when Iullus intended to write a higher kind of poetry praising Augustus for his success in Gaul.
[6] Iullus was also a poet and is credited with having written twelve volumes of poetry on Diomedia some time before 13 BC, which has not survived.
Julia's marriage to her stepbrother had become a disaster and she was desperate to divorce him, and Iullus was open to satisfy her desires.
Both contemporary and modern historians have suggested Iullus had designs upon the monarchy[8] and wanted to marry Julia before her children Gaius and Lucius came of age possibly to form some sort of regency.
When Augustus took action on his daughter Julia's copious promiscuity, Antonius was exposed as her prominent lover.
Modern scholars have speculated that Iullus Antonius is one of the figures represented on the north face of the Ara Pacis, a Roman altar.