Tiberius (42 BCE to 37 CE) was the second Roman emperor, who reigned from 14 to 37 CE. The adopted son of Augustus, he led a long and tormented life of service to the Roman Empire before becoming princeps (emperor) in 14 CE. Though he was never popular, his rule started off well. But his jealousy towards his heir Germanicus and his aloofness during the treason trials orchestrated by the crafty Praetorian prefect Lucius Aelius Sejanus lost him any goodwill that he had with the Roman Senate. He spent his final years alone, in voluntary seclusion on the island of Capri, until his death in 37 CE.

On 16 November 42 BCE, Tiberius Claudius Nero was born amidst an apocalypse. The assassination of Julius Caesar two years prior had thrust the Roman world into chaos and civil war. After Caesar's assassins – led by Marcus Junius Brutus and Gaius Cassius Longinus – had met their bloody ends on the battlefields of Philippi, the heirs of Caesar had formed a power-sharing alliance known as the Second Triumvirate and now ruled through terror. They proscribed and liquidated prominent Romans suspected of treachery, seizing their properties. No one was safe, not even the gens Claudia, the ancient and distinguished patrician family into which Tiberius had been born. His father, also named Tiberius Claudius Nero, was acutely aware of his family's long history of republican virtue and sought to do what he could to preserve the liberties of the dying Roman Republic.

Before long, the triumvirate fractured, pitting one triumvir, Caesar's adopted son Octavian, against another, Mark Antony. Viewing Octavian as the greater evil, the elder Tiberius threw his lot in with Antony. He took his wife, Livia Drusilla, and their infant son and fled, first to Sicily and then on to Greece, hounded all the way by Octavian's soldiers. Once, while on the run in Greece, the family made a dramatic escape through a forest fire, the flames nipping at their heels and even scorching Livia's clothes and hair. In 39 BCE, Octavian and Antony signed a peace treaty, which granted amnesty to all political exiles like Tiberius Nero and his family. When they returned to Rome, the young and beautiful Livia quickly caught Octavian's eye. They began an affair and – after Livia had given birth to her second son, Drusus – divorced their respective spouses. When Octavian and Livia married in 38 BCE, Tiberius Nero gave the bride away as if he were her father.

The younger Tiberius and his brother Drusus were raised by their father for the next several years until his death in 33 BCE. Though he was only 9, Tiberius delivered the eulogy at the funeral. Afterwards, the brothers were raised by their mother and stepfather, who would soon be recognized as princeps ('First Citizen') of Rome and granted a new name: Augustus. Growing up under the roof of the most powerful man in Rome, Tiberius received an excellent education. He was trained in the Greek and Latin classics, developed an affinity for philosophy, and became skilled in oratory and poetry. Since Augustus had no sons of his own, Livia hoped to position her own boys to be his heirs and urged her husband to fast-track their political careers. In 24 BCE, in accordance with her wishes, 17-year-old Tiberius received the office of quaestor and, a few years later, married Vipsania, daughter of Augustus's right-hand man Marcus Agrippa. It was a bright start to what was destined to be a turbulent and troubled life.

Throughout the next decade, the sons of Livia spent much of their time on military campaigns, fighting Rome's enemies in the snow-covered Alps, along the waters of the Danube, and in the dark forests of Germany. Though Tiberius was never as popular as his charming younger brother, his austerity and serious demeanor were appreciated by the Roman people. His pale, gloomy face and broad, stooped shoulders seemed to indicate that he was carrying the storied legacy of the Claudian family on his back. In 13 BCE, he was elected consul for the first time, shortly after the birth of his only son, whom he named Drusus after his beloved brother. The following year, Augustus decided it was time to elevate his two stepsons in the line of succession. To strengthen his ties with the August Family, Tiberius was ordered to divorce Vipsania to marry Julia the Elder, Augustus's daughter.

Tiberius seems to have taken this hard, as he had genuinely been in love with Vipsania. Once, when he happened to see his ex-wife out in public, the heartbroken Tiberius trailed after her with "his eyes so full of tears, his gaze so sorrowful" (Suetonius, Tiberius, 7). Augustus was not happy when he heard what had happened and took steps to ensure that the two would never meet again. By contrast, Tiberius despised his new wife, Julia, who appears to have hated him, too.

He did not have to share her bed for long, however, for he was often off on campaign, expanding the empire's frontiers. Between 12 and 9 BCE, he played a major role in the conquest of Pannonia in Central Europe. But he hardly had time to bask in his victory when he received more terrible news: while leading troops in Germany, his brother Drusus had been thrown from his horse and was barely clinging to life. Tiberius rushed to Drusus's camp, only to find that his brother was already dead. Bereft, Tiberius accompanied the body back to Rome, traveling the entire distance on foot.

By this point, Augustus had adopted his two young grandsons, Gaius Caesar and Lucius Caesar, as his heirs. The Roman people seemed equally as enamored with these princelings as Augustus, showering them with love and praise whenever they appeared at public events. For Tiberius, who had spent his life in service to Rome, to be passed over by two untried boys was more humiliation than he could take. In 6 BCE, when Augustus ordered him to go lead a campaign in the East, Tiberius flat-out refused and instead announced that he was retiring.

After an argument with the princeps, Tiberius left Rome and went to Rhodes, where he spent the next few years reading Greek literature and talking with philosophers. But if Tiberius hoped that distance would make the hearts of his countrymen grow fonder, he was wrong; within a few years, he had been all but forgotten in Rome. Realizing his mistake, he frequently petitioned Augustus to be allowed to return home but was denied each time. The respect that he had spent decades building had deteriorated to a dangerous point. Once, at a dinner party, a companion of young Gaius Caesar drunkenly offered to go to Rhodes and bring back the head of the 'exile'. Though Gaius had refused, the story alarmed Tiberius, who realized that he had been rendered powerless.

But just when Tiberius was at his lowest, fate intervened. First, Lucius Caesar died after a sudden illness in 2 CE. Then, less than 14 months later, Gaius, too, had died unexpectedly. At a stroke, Augustus had lost both of his heirs and was forced to re-examine the line of succession. Although he adopted his only surviving grandson, the teenage Agrippa Postumus, he realized that the boy was too young and inexperienced to succeed him. He was forced, therefore, to turn to Tiberius, who was now one of the only adult candidates left standing. Augustus formally adopted Tiberius; now known as Tiberius Julius Caesar, the gloomy general was finally his stepfather's heir. But in turn, Tiberius was required to adopt his dashing and popular nephew, Germanicus, who would become second in line to the throne.

Tiberius returned to Rome, a homecoming made even sweeter by the fact that his hated wife, Julia, had been exiled on charges of adultery (she would eventually die in exile). In 9 CE, he led an army into Dalmatia with Germanicus serving as one of his lieutenants. By 13 CE, the aging Augustus had given Tiberius powers equal to his own, effectively making him co-princeps. As shrewd as ever, Augustus had done this to ensure a smooth transition of power, for he felt his own mortality. Indeed, on 19 August 14 CE, he died at the age of 75. He was not happy about who he was leaving to succeed him. After his last conversation with Tiberius, the dying princeps had apparently lamented the fate of the Roman people, who would now be "ground between such remorseless jaws" (quoted in Holland, 183). Augustus would not be the only member of the House of Caesar to die that year. Around the same time, young Agrippa Postumus was murdered by one of his own guards. Though Tiberius would always deny involvement, many suspected he had given the order, to remove his last obstacle to power.

On 17 September 14 CE, Tiberius appeared before the Senate. Like Augustus before him, he made a show of false modesty, feigning reluctance to rule as princeps – he was already in his mid-50s with failing eyesight, he said; let the Senate rule. But the senators understood how the game was played and begged him to pick up his stepfather's mantle, asking, "How long, O Caesar, will you suffer the Republic to lack a head?" (quoted in Holland, 186). Thusly confirmed in his powers, Tiberius initially worked to show that he was a friend of the Senate. He frequently attended Senate meetings, allowing senators to speak their minds freely and remaining discreet with his own opinions. He also deprived the plebeians of their right to vote for magistrates – from now on, consuls would be selected in the Senate House. Though this pleased many conservative aristocrats, Tiberius was offput by how quickly the Senate had submitted to him. Once, when leaving the Senate House, he remarked that the senators were men fit to be slaves.

He was a notorious miser who looked for ways to penny-pinch wherever he could. In one famous incident, he served his dinner guests only half a boar on the grounds that "it was just as good as a whole one" (Suetonius, Tiberius, 34). He reduced the costs of games and gladiatorial shows, much to the displeasure of the masses. But perhaps the most consequential example of his frugality was his decision to suspend any further military conquests. Military campaigns were expensive, and Tiberius opted to cut costs by using the army to simply defend the existing borders. With some exceptions – most notably the invasion of Britain in 43 CE – his successors stuck to this policy, and the borders of the Roman Empire remained largely static. But while Tiberius certainly wanted to save money, he had an ulterior motive in halting future conquests, as he did not want any general to become popular enough to challenge him. For Tiberius was a jealous man, indeed.

This jealousy reared its ugly head regarding Tiberius's heir, Germanicus. In 14 CE, Germanicus quelled a mutiny among the legions of the Rhine frontier and spent the next two years covering himself with glory in battle against the Germanic tribes. In 17 CE, Tiberius recalled Germanicus and awarded him a Roman triumph; as the young and handsome general paraded down the streets in his chariot, cheered by the masses, the gloomy and uncharismatic princeps stewed. The following year, Tiberius sent Germanicus on a diplomatic mission to the eastern provinces. When he arrived in Antioch, Germanicus ran afoul of the governor of Syria, Gnaeus Calpurnius Piso; it was rumored that Piso was acting on secret orders from Tiberius to undermine Germanicus's authority at every turn. The rivalry between the two men intensified until 10 October 19 CE, when Germanicus died after a brief illness. Rumor spread that Piso had poisoned him, perhaps at Tiberius's behest. Piso was summoned to Rome to stand trial for the murder, but he committed suicide before a verdict could be reached.

The death of Germanicus meant that Tiberius's natural son, Drusus the Younger, now stood as heir. Though much more of a playboy than his heroic adopted brother, Drusus certainly had the charisma and popularity necessary for the role. In 21 CE, he served as consul alongside his father, a sure sign of his rising star. But Drusus's new position put him in the crosshairs of a dangerous and power-hungry man. Lucius Aelius Sejanus was the prefect of the Praetorian Guard and had spent the last few years slowly increasing his influence over the princeps. Tiberius trusted Sejanus implicitly – once even referring to him as 'partner in my toils' – and often elevated his supporters to lofty government positions. Drusus clearly saw that Sejanus was overstepping himself and made no secret of his hatred for the man. In 23 CE, their rivalry reached a boiling point when Drusus punched Sejanus in the mouth. Shortly thereafter, Drusus was dead; naturally, people began to whisper that he had been poisoned by the Praetorian prefect.

Whether Sejanus had murdered Drusus or not, he resolved to pave his path to power by trampling over other members of the imperial family. He next targeted Agrippina the Elder, Germanicus's widow, who had long suspected that Tiberius was behind her husband's death. It did not take much for Sejanus to convince the princeps that Agrippina was plotting against him, conspiring to put one of her own sons on the throne. Tensions between the two reached such a point that Agrippina refused Tiberius's offer of an apple at the dinner table, believing it to have been poisoned. With Tiberius's approval, Sejanus began arresting many of Agrippina's allies in the Senate and charging them with maiestas, a vague crime associated with treason. One senator committed suicide, while several others were exiled. After being politically isolated, Agrippina was eventually exiled to the barren island of Pandateria, where she soon starved to death. Her two eldest sons were also exiled and died under suspicious circumstances.

In 26 CE, Tiberius left Rome for good, retiring to the island of Capri in the Bay of Naples. Sejanus remained in Rome, acting as though he were the princeps's mouthpiece. He purged his political enemies in the senatorial and equestrian classes, accusing them of maiestas; many were put to death. But even as he had the entire Roman world in his grasp, Sejanus was still at Tiberius's mercy. In 31 CE, Tiberius's former sister-in-law, Antonia Minor, sent him a letter, accusing Sejanus of conspiring to usurp the throne. In October of that year, Sejanus was summoned to the Senate House, where a letter from Tiberius was read out, condemning him as a traitor. Sejanus was arrested, tried, and executed. In the months that followed, his close family members and political supporters were also executed, their bodies dumped on the Gemonian Steps before being dragged away on hooks and thrown into the Tiber River. Much to the horror of the Senate, the treason trials did not die down after Sejanus's fall, but accelerated. The new Praetorian prefect, Naevius Sutorius Macro, was just as adept at sniffing out treason as his predecessor, and in Rome, the blood continued to flow. According to the historian Suetonius:

Not a single day went by without an execution…many were charged and condemned alongside their own children…of those who were summoned to plead their cases, some – out of a desire to avoid the misery and disgrace of what they knew was their inevitable conviction – drank poison right in the Senate House; there were others too who opened their veins at home, but these, because their wounds could be bandaged up, were still carted off to prison, albeit twitching and half-dead.

(Suetonius, Tiberius, 61)

As his dreaded treason trials played out in Rome, Tiberius spent his final years in seclusion on Capri. Indeed, he did not even return to Rome for the funeral of his mother, Livia, when she died in 29 CE. Romans were naturally suspicious of too much privacy, and vile rumors quickly spread about the cruel and depraved activities that the old princeps was getting up to. According to one story, he was surprised by a fisherman who had climbed up the island to present him with a mullet as a gift; Tiberius ordered his guards to seize the poor man and scrub his face with the fish. He was also said to have given in to his most perverse sexual fantasies, which included having young boys swim in between his legs. How many of these stories were true and how many were hearsay is impossible to know for certain.

By 35 CE, Tiberius realized he needed to shore up his own line of succession. There were two candidates – Gaius Caesar, the only surviving son of Germanicus and Agrippina, who is more commonly known by his nickname Caligula, and the princeps's teenage grandson, Tiberius Gemellus. Tiberius ended up naming them both joint heirs in his will, although he sensed Caligula's propensity for cruelty, commenting that he was rearing a viper for the Roman people. On 16 March 37 CE, Tiberius died at the age of 77. Though he was an old man who had been ill, some ancient sources accuse Caligula of having hurried his death along by smothering him with his bedclothes. According to another tale, Tiberius, having been confined to his sickbed for some days, called for his attendants. When none came, he tried to stand, but collapsed and died. Back in Rome, people cheered his death, shouting, "To the Tiber with Tiberius!" But if they were relieved to be free from his tyranny, they would soon learn that he would be succeeded by an even worse tyrant.