Commodus and Lucius Antistius Burrus served as consuls for the year 181. The year passed and nothing worth recording happened. The borders were secure, the provinces prospered and the new Augustus seemed to cooperate well with the Senate. That would change dramatically the next year.
In 182, one Ummidius Quadratus and Commodus’ sister Lucilla hatched a plot against their emperor. Lucilla had first been married to Lucius Verus (130-169), who was her father’s adoptive brother and who had served as co-emperor since 161. When Verus died, Marcus Aurelius married off his daughter to Tiberius Claudius Pompeianus, a man who had served the emperor well. Lucilla had kept her imperial privileges. She was allowed to sit in the imperial lodge in theatres and the sacred fire was carried before her when she travelled. Lucilla was not the only one with imperial privileges, however. Her brother Commodus had married Bruttia Crispina in 178 and Crispina was now the emperor’s wife and First Lady of the Empire. Herodianus writes that “Lucilla found this difficult to endure, and felt that any honor paid to the empress was an insult to her”. It may therefore have been jealousy that made her orchestrate her conspiracy.
Lucilla told nothing to her husband Pompeianus, who was still loyal to Commodus. She found an ally (and, according to rumours, a lover) in Ummidius Quadratus, a young and rich nobleman from a distinguished family. Several senators joined the plot to murder the emperor, and the plan was to be executed by a senator named Claudius Pompeianus Quintianus. It is not very clear who he was. Dio claims he was Lucilla’s daughter’s fiancée, who had an intimate relationship with his future mother-in-law as well. Yet he may also have been a nephew or cousin of Lucilla’s husband, or his son from a previous marriage (and thus Lucilla’s stepson). Whoever he was, his attack on the emperor failed miserably.
Quintianus hid in the entrance to an amphitheatre – the precise location is unknown – and waited until the emperor appeared. When Commodus entered, he pulled out a dagger or a sword from under his clothes and shouted that this weapon had been sent by the Senate. Then, things went horribly wrong. Herodianus writes that:
“Quintianus wasted time making his little speech and waving his dagger; as a result, he was seized by the emperor’s bodyguards before he could strike, and died for his stupidity in revealing the plot prematurely.”
He was not the only one to die. Although there is no evidence to suggest that the conspiracy was widely supported by the Senate, the fact that senators had participated in it permanently damaged the emperor’s relationship with this body. Lucilla’s involvement was discovered, and Commodus banished his sister to the island of Capraea (Capri). Later, he had her executed there. Ummidius Quadratus was also killed.
– Adrian Goldsworthy, The Fall of the West, p. 54-55.