Short answers, pulled from the story.
Quintus Caecilius Metellus Numidicus was a Roman statesman and general, born around 155 BC, who served as consul in 109 BC and commanded Roman forces in Africa during the Jugurthine War. He was the leading figure of the Optimates, the conservative faction of the Roman Senate, and a bitter political opponent of Gaius Marius. He is remembered for his reputation for integrity in an era of growing political corruption.
Metellus received the agnomen Numidicus after returning from his command in North Africa, where he fought against Jugurtha during the Jugurthine War. He was granted a triumph by the Roman people and senators who supported him, and the surname Numidicus honored his campaign in Numidia.
Metellus was exiled after he refused to swear allegiance to an agrarian law proposed by the tribune Lucius Appuleius Saturninus and Marius, which required all senators to take a personal oath of obedience under penalty of expulsion and a heavy fine. He was the only senator to refuse. Saturninus then proposed a law specifically to banish him. Metellus chose to leave voluntarily rather than allow his supporters to defend him by force, spending about a year in Rhodes.
Metellus Numidicus returned to Rome in 99 BC, after the tribune Quintus Calidius proposed a law permitting his return. His son, later known as Quintus Caecilius Metellus Pius, earned the cognomen Pius for his faithful efforts in supporting that proposal.
Marius served as second-in-command under Metellus during the Jugurthine War and spread rumors that Metellus was prolonging the war to keep his command. Marius then returned to Rome, won election as consul for 107 BC, and displaced Metellus as commander in Numidia. Their conflict continued in Rome, where Metellus, as censor in 102 BC, tried unsuccessfully to expel Marius' ally Saturninus from the Senate, and later refused the oath that Marius ultimately took.
Metellus was sent to Athens in his youth, where he studied under Carneades, a celebrated philosopher and renowned teacher of oratory. He returned to Rome with strong oratorical skills, which Cicero later praised.