Sir Toby Belch, Olivia’s uncle, is a hard-drinking partygoer whose joie de vivre and high spirits stand in stark opposition to the character of Malvolio in Shakespeare’s play. But he is no fool. Although Sir Toby speaks highly of Sir Andrew, claiming he can speak many languages, we quickly learn that Sir Andrew is an ill-educated fool who would rather spend his time watching bear-baiting than mastering ‘tongues’ or languages. It becomes clear that Sir Toby Belch is simply stringing his poor friend along, convincing him that he stands a chance with Olivia so that Sir Andrew will continue to hang around and be Sir Toby’s drinking companion (and, most likely, fund their drinking bouts). Both Sir Andrew and Malvolio are thus similarly duped by Sir Toby, who – acting on different motives in each case – persuades them both that his niece fancies them, when he knows full well that neither of them stands a chance.
Sir Toby Belch’s most famous line in the play is his riposte to the puritan Malvolio: ‘Dost thou think, because thou art virtuous, there shall be no more cakes and ale?’ In other words: does Malvolio think, because he abstains from life’s worldly pleasures, everyone else will give them up too? Sir Toby’s very surname, Belch, is a none-too-subtle signifier of the character’s delight in food and drink and hearty living, to say nothing of his noisy and uncouth side.
And Sir Toby’s main role in the plot of Twelfth Night is his involvement in the plot to trick Malvolio, Olivia’s steward, into believing that Olivia loves him. It’s clear that Malvolio wishes to lord it over Sir Toby, Olivia’s uncle, and that becoming the lord of the house, by marrying Olivia, Malvolio would be able to boss about Sir Toby (his social superior, as Sir Toby’s knighthood suggests). Sir Toby’s part in Maria’s plot to bring down Malvolio a peg or two is thus motivated by revenge: Sir Toby is sick of Malvolio attempting to boss him about, chastising him for coming home late and disturbing everyone with his drunken, boisterous behaviour.