Who is Marcus Calpurnius Bibulus from Caesar's Women and what is their importance?

Marcus Calpurnius Bibulus is a wealthy plebeian and one of the boni. He has hated Caesar since he gave him the nickname the "Flea", something he is still called behind his back. Bilbulus works toward blocking Caesar's legislation and election to Pontifex Maximux, and he opposes Caesar no matter the issue.