Homosexuality was not such a taboo among the Romans- what was an issue was who assumed the active and passive roles. It was common for political enemies to spread rumors concerning their opponents, regardless of whether they were Emperor or Aedile. It is very difficult or impossible for modern scholars to differentiate between fact and fiction in these cases.
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It would certainly appear that Augustus was gay and that his lover/life mate was Marcus Agrippa, although Agrippa was likely predominantly heterosexual. Despite Augustus' much vaunted affairs with women (me thinks thou does't protest too much), Octavian/Augustus produced only one heir, a daughter, Julia, and that in his youth, with hormones raging, as any male, gay or straight can do. It is certainly plausible that the his much hyped affairs with women were a smokescreen to avoid the disparaging accusations that plagued his deified mentor and adoptive father, Julius Caesar, throughout his lifetime. Although likely predominantly heterosexual, Caesar never escaped his critics' slurs that in his teens he was butt-boy to Nicomedes, the King of Bithynia, in Asia Minor. (Belittled as "every woman's man, and...every man's woman," Caesar was reportedly lecturing Rome's Senate about Rome's obligations to Nicomedes when Cicero sneered, "No more of that, pray, for it is well known what he gave you, and what you gave him in turn..") Julius Caesar tried unsuccessfully all of his life to overcome the ridicule by bedding every woman who walked, to no avail. It would be a powerful lesson to young Augustus, who unlike Caesar, was likely gay, and a lesson he never forgot.
Though still quite young, Augustus never impregnated his second wife, Livia, in over fifty years of marriage, despite her obvious fertility, having previously produced no less than three sons in her short marriage to her previous husband Tiberius Claudius Nero.
Agrippa was brilliant even as a young soldier, and was likely responsible for young Octavian's/Augustus' defeat of the battle-tested Marc Antony and Cleopatra, at the battle of Actium despite Egypt's overpowering fleet.
Agrippa was ever-faithful to Augustus, who, despite Agrippa's low birth, raised him to co-consul status. Augustus preferred Agrippa even over his own sister Octavia's son, Marcellus, (who was married to Julia), giving Agrippa his signet ring when Augustus fell ill in 24 BC. Upon the death of Marcellus (likely poisoned by Augustus' wife Livia), Augustus did the next best thing to marrying Agrippa himself and married him to Julia. They produced several sons, two of whom Augustus adopted and recognized as his heirs, acknowledging them as the princes of the kingdom.
Although it would appear that Augustus was thoroughly gay, it would appear that Agrippa was predominantly not, although male-male sex was common to most all Romans. Whether a sexual relationship continued throughout adulthood, Agrippa obviously loved and remained devoted to Augustus all of his life. Their partnership is one of the world's great male love stories.
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