Baltar is a brilliant but narcissistic scientist who unwittingly aided the original Cylon destruction of the 12 Colonies. He subsequently became a full-fledged Cylon collaborator: As the President, he surrendered New Caprica to them, and after the evacuation of New Caprica he traveled with their fleet and explored their spiritual beliefs until he was recaptured by his fellow humans. While awaiting trial for treason in the Galactica's brig, he won the affection of many of the Colonial fleet's downtrodden by writing a manifesto that detailed his poverty-stricken childhood and excoriated society's "elites." Upon his acquittal and release, his most devoted followers have begun to treat him as a holy man. They may not be wrong: Baltar's ostensibly mystical visions of the beautiful Cylon Number Six remain unexplained.
When the Spartacus Rebel Army takes the valley, everyone finally gets a chance to party and celebrate the fact that Crixus is leaving. And Agron and Nasir have one of their best scenes ever
Crixus, the undefeated Gaul. The Primus. The dude who saved Naevia. And the tragic and yet somehow noble end of his story.
When the Romans take the city, Spartacus decides their best move is to run. And Gannicus proves himself worthy of all the praise that's so often heaped on him.