Catalyst for Conflict: Sir Toby's excessive drinking and rowdy behavior create tension within the household and contribute to the play's central conflict. His actions lead to the prank on Malvolio, which sets in motion a series of events that ultimately lead to the play's resolution.
Comic Relief: Sir Toby also serves as a source of comic relief. His drunken antics, boisterous personality, and mischievous nature provide moments of humor and lightheartedness amidst the play's more serious themes of love, deception, and mistaken identity.
Overall, Sir Toby's contributions to the play enhance its dramatic tension and provide a counterpoint to the play's more serious moments.