Rome's first co-emperor got the job because Marcus Aurelius insisted
When Antoninus Pius died in 161, the Senate meant to crown Marcus Aurelius alone. Marcus refused unless his adoptive brother Lucius shared equal powers. So for the first time Rome had two emperors at once, a pattern that would recur often later. The junior partner, Lucius Verus, is far less remembered.
He was born Lucius Ceionius Commodus in Rome on 15 December 130, son of Lucius Aelius Caesar, Hadrian's first chosen heir. When that father died on 1 January 138, Hadrian picked Antoninus instead and required him to adopt both Lucius and the young Marcus. The marriage plans were reshuffled too: Antoninus's daughter Faustina, first promised to Lucius, went to Marcus. Lucius was tutored by the celebrated teacher Fronto, wrote poetry, and became quaestor in 153, a year below the legal age.
On taking power, Lucius dropped the name Commodus and adopted Verus, Marcus's own former cognomen. Equality was mostly on paper: Marcus had held one more consulship, alone served as chief priest, and carried more authority. Lucius handled the ceremony at the Praetorian camp, promising each guardsman 20,000 sesterces, double any earlier gift and worth several years' wages. The pair were popular for their lack of pomp and tolerated open mockery by the comic writer Marullus. Fronto, visiting after the accession, called on Marcus alone; Lucius's letters to him asked for rulings on which of two actors was better.
Trouble came fast. In spring 162 the Tiber flooded much of Rome, leaving famine behind. In the east, Vologases IV of Parthia had seized Armenia, a Roman client, in 161. The governor of Cappadocia, Severianus, reportedly encouraged by the confidence trickster Alexander of Abonoteichus and his snake Glycon, led a legion to disaster at Elegeia within three days, and the Syrian army was also beaten. Marcus had no military experience, so legions were pulled from the Rhine and Danube.
Most of Lucius's reign was spent directing that Parthian war, which ended in victory and some territorial gains. He then took part in the opening phase of the Marcomannic Wars, but sickness killed him in 169, and the Senate declared him the Divine Verus.
Source: Lucius Verus
