Tiberius Gemellus

• 1. Introduction

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  Tiberius Gemellus was born on the 10th of October AD 19, the same day his uncle Germanicus died far away in Syria. He was a grandson of the emperor Tiberius and a first cousin of Caligula, the man who would one day rule Rome. By the year 35, Tiberius named him joint heir to the empire alongside that same cousin. That plan rested on the deaths of nearly everyone else who once stood in line for power. Within a few years Gemellus was dead too, killed or made to take his own life on Caligula's order. How did a household meant to produce Rome's next ruler destroy almost every candidate but two? And once Gemellus and Caligula were named heirs together, what turned that partnership fatal?

• 2. A Birth Celebrated in Rome

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  Gemellus took his name from a Latin word meaning "the twin." He was born alongside a brother, Germanicus Gemellus, who died as a young child in AD 23.

  Tiberius insisted that no Roman of Drusus's high rank had ever fathered twins before, and moneyers stamped the news onto the reverse of coins.

  His paternal grandparents were Tiberius and Vipsania Agrippina, while his mother's parents were the general Nero Claudius Drusus and Antonia Minor. A younger sister, Julia Livia, completed the family alongside the twins.

  Through this web of relations, Gemellus stood close to all five Julio-Claudian emperors. He was Tiberius's grandson, Augustus's adopted great-grandson and great-grandnephew, Claudius's nephew, Caligula's cousin, and Nero's first cousin once removed.

  None of those five imperial bonds would protect his father, Drusus, or his cousins Nero and Drusus, from what was coming next.

• 3. The Fall of the Heirs

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  In the spring of 22, the Senate granted Drusus the tribunicia potestas, a clear signal that Tiberius intended his son as heir.

  The following year brought a rupture between Drusus and Lucius Aelius Sejanus, the praetorian prefect who commanded Rome's soldiers in the city. Tacitus records that Sejanus began plotting to secure his own position against Drusus. On the 14th of September AD 23, Drusus died in a way that at first looked natural. Cassius Dio and Tacitus both concluded that Livilla poisoned her husband at Sejanus's urging, though the true cause of their quarrel remains unknown.

  Drusus's death devastated Tiberius and put the future of the principate in doubt, yet he still trusted Sejanus completely. Because Gemellus was too young to be named heir, Tiberius adopted Germanicus's sons, Nero and Drusus, and presented them to the Senate as his successors. Nero received the quaestorship five years ahead of the usual age and married Gemellus's sister, Livia, joining the two branches of the family. Neither of them would live to succeed Tiberius.

  By 26, Tiberius had withdrawn from politics and retired to the island of Capri, leaving Sejanus in charge of Rome. In 28 or 29, the Senate charged Nero with homosexuality and exiled him to the island of Ponza. Germanicus's other son, Drusus, was locked in a dungeon beneath the Palatine Hill and starved there. Nero died in exile in 33. Suetonius claims Tiberius had encouraged Sejanus's rise specifically to clear the succession for Gemellus, his own blood grandson, over Germanicus's sons.

  Sejanus himself fell suddenly, executed in October of 31 for reasons that still remain unclear. Eight days later, on the 26th of October AD 31, his wife Apicata took her own life. Cassius Dio reports that she left behind a message accusing Livilla and Sejanus of murdering Drusus together.

  The historian Barbara Levick offers a skeptical counter-reading of Apicata's message. She argues Sejanus killed Drusus in self-defense, since only Tiberius stood between the prefect and ruin at Drusus's hands. She also considers it unlikely that Livilla would have helped destroy the family that secured her children's future. She dismisses Apicata's story as the revenge of a wife abandoned for someone else.

  Only two of Tiberius's male descendants now remained as realistic heirs, his grandson Gemellus and Germanicus's elder son, Gaius, known to history as Caligula.

• 4. Two Heirs, One Empire

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  Because no formal mechanism existed for choosing a new emperor, Tiberius's only real tool was his own will, the document that would determine who inherited his estate.

  Suetonius reports that Tiberius harbored suspicions about Gaius but actively detested Gemellus, believing him the result of an affair by his mother, Livilla. Gemellus's youth worked against him as Caligula's standing rose. Caligula was made quaestor in 33 and summoned to join Tiberius on the island of Capri that same year.

  In 35, Tiberius formally named both grandsons as joint heirs to his estate. Tacitus records a moment on Capri when Tiberius, holding Gemellus in his arms while looking at Caligula in tears, warned him: "You will kill him, and another will kill you."

  Tiberius died on the 16th of March AD 37, clearing Caligula's path to the throne. With help from the praetorian prefect Macro and that year's consuls, Caligula had Tiberius's will nullified. That act let him claim the entire estate Gemellus was meant to share.

  Caligula then granted Gemellus the toga virilis, adopted him formally, and brought him into the Arval Brethren priesthood. He also named him princeps iuventutis, leader of the youth. His tirocinium, the ceremony marking a young Roman's eligibility for military service, took place in July of 37. That same year, Caligula distributed a congiarium of 75 denarii to every citizen in Rome.

  Both Tacitus and Suetonius describe Gemellus as still a child that year, even though he had already turned 18. Historians read that as a note about his mental development rather than his age. That may explain the delay in granting him the toga of manhood.

  The philosopher Philo viewed the adoption as a maneuver, placing Gemellus under Caligula's patria potestas, his legal power as a father. Philo suggests the move may have helped persuade the Senate to accept the cancellation of Tiberius's will. Adopting his rival, in other words, bought Caligula time to settle the succession on his own terms.

  Caligula would not let that arrangement last past the following year.

• 5. A Forced End

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  When Caligula fell seriously ill, Gemellus's life ended soon after, in late 37 or early 38.

  Cassius Dio places this death alongside that of Caligula's father-in-law, Marcus Junius Silanus, both falling in late 37. Their replacements in the Arval Brethren were not appointed until the 24th of May AD 38.

  Dio adds that Gemellus was waiting for an opportunity to benefit from Caligula's illness, while Philo says Caligula's stated justification was an alleged conspiracy. Suetonius offers a stranger detail. Gemellus was taking medicine for a chronic cough. When the smell was noticed, it was treated as evidence he had taken an antidote against poison.

  Caligula ordered him to die by his own hand. Soldiers handed him a sword and had to guide it themselves, since Gemellus reportedly did not know how to use it on himself.

  According to Dio, the formal charge against Gemellus was that he had prayed for, and anticipated, Caligula's death.

  The historian Anthony Barrett notes that Gemellus would have stood in for an ill Caligula at nonpolitical events. His uncle Claudius represented the emperor at public games instead. Barrett suggests Caligula grew paranoid about anything done in his name. Gemellus's only known supporter, Aulus Avilius Flaccus, the prefect of Egypt, believed he deserved to co-rule.

  Caligula never reported the death to the Senate, and Gemellus's tomb does not even acknowledge his adoption by the emperor. That silence would not last forever, and centuries later his story would surface again, not in Roman inscriptions but on screen.

• 6. Gemellus on Screen

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  Douglas Melbourne played Gemellus in "Zeus, by Jove!", an episode of the 1976 BBC series I, Claudius.

  Bruno Brive took on the role in the 1979 film Caligula.

  Leon Wadham portrayed Gemellus in the third season of the Netflix series Roman Empire.

  Of the three, only Roman Empire brings Gemellus's story to a streaming audience, keeping a minor Julio-Claudian heir circulating in modern popular memory.