Dio and Suetonius state that Octavian killed Antony's son Marcus Antonius Antyllus and Cleopatra's son with Julius Caesar, Caesarion. The only further mention of Alexander Helios and Ptolemy Philadelphus comes from Cassius Dio, who states that when their sister Cleopatra Selene II married King Juba II, Octavian (then named Augustus) spared the lives of Alexander Helios and Ptolemy Philadelphus as a favor to the couple. After Helios arrived in Rome, he disappears from historical records. See also List of people who disappeared References Sources Cleopatra Selene II & Juba II Plutarch - Antony 1st-century BC Egyptian people 20s BC deaths 40 BC births Fraternal twins Ptolemaic dynasty Roman-era Egyptians Egyptian twins Year of death unknown Children of Cleopatra Children of Mark Antony