He was an associate of Marcus Aemilius Lepidus, who led a revolt against the senate after the death of Sulla.
[10][11] Brutus was stationed at Mutina, where he defended the stronghold against Pompey, who had been sent by the senate to dislodge him.
John Leach, in his biography of Pompey, defends his subject by arguing that Brutus "presumably began to whip up further support for Lepidus (the name of the town suggests that there were hereditary clients of his there)" and so Pompey was "forced" to send Geminius to Regium Lepidi to recapture and execute him.
His homonymous son by Servilia is the Marcus Junius Brutus who was one of the chief assassins of Julius Caesar.
[6][1] The assassin was adopted by one of his maternal relatives, becoming Quintus Servilius Caepio Brutus; if this Brutus was proscribed, the adoption would have had the effect of lifting any civic disabilities – persons proscribed and their heirs were barred from seeking political office at Rome – that transmitted to his son.