His sons were Quintus Fulvius Flaccus (consul 179 BC) and Lucius Manlius Acidinus Fulvianus (consul 179 BC), was adopted into the Manlia gens, probably by Lucius Manlius Acidinus - the only instance of two brothers holding the consulship at the same time during the Republic.
He was again consul in 212 BC, during the Second Punic War, winning a victory over Hanno, son of Bomilcar and capturing his camp at Beneventum.
Quintus Fulvius Flaccus was one of the three candidates for the position of Pontifex Maximus c. 212 BC, when he and another senior candidate Titus Manlius Torquatus, both former censors, were pipped at the post by a younger man, Publius Licinius Crassus who was not yet a curule aedile and thus probably aged in his middle thirties.
Flaccus was known for his severity towards the disloyal citizens of Capua, of whom he had the senior men executed and the rest of the citizenry condemned to slavery for their disloyalty to Rome.
He attempted to warn Tiberius Gracchus of the plots against his life on the day that he was killed; in 121 BC, having supported Gaius Gracchus in his reform program and tried to lead an armed resistance against the Senate, he and his elder son were tracked down and executed (beheaded) without trial on the orders of the consul Lucius Opimius; the youngest son, too young to have participated in any plotting or armed revolt, died in prison, again without trial (another son was apparently the father of Fulvia, third wife of Mark Antony).