The two male comic characters, while considered as a sort of team, represent the opposite sides of a coin. Sir Toby Belch, as his name indicates, is earthy, crude, very fat, and jolly. Sir Andrew Aguecheek, as his name might indicate, is tall, long, thin, and balding.
Sir Toby is also the opposite to Sir Andrew in intellect. Sir Toby is actually a sharp, witty person who, even when he is drunk, is capable of making a good pun or of creating an ingenious and humorous plot complication. For example, he appreciates Maria not for her looks or for romantic matters, but because she is capable of contriving such a good joke against Malvolio. We are not surprised, at the end of the play, when he marries her.
Sir Toby's character is similar to an earlier comic character of Shakespeare's, Sir John Falstaff. Both characters share many of the same qualities. For example, both of them are given to excessive drinking and eating, both love a good prank, and both enjoy harassing serious-minded people like Malvolio. Thus, while Sir Toby is a knight, he is still a rather corrupt individual. After all, the only reason he keeps Sir Andrew Aguecheek around is to gull him out of his money. The fact that he can tease and play jokes on Sir Andrew is secondary to his primary purpose of using Sir Andrew's money to continue drinking. He is indeed guilty of misusing his niece's house and of abusing her servants; yet in spite of all of his faults, Sir Toby is, perhaps, Shakespeare's most delightful comic creation, after Sir John Falstaff.
Sir Andrew Aguecheek, on the other hand, is merely a foolish fellow who is easily gulled and who does not realize that he has been cheated. It would take a very foolish fellow to think that such a rich and beautiful lady as Olivia would seriously consider this "ague"-looking, skinny, balding, and ugly man as a possible suitor. In addition, he is a coward, and a good deal of the humor surrounding him comes from how he is tricked into fighting with Cesario, and then later, what happens when he encounters Sebastian. Sir Toby sums up this comical knight with the comment: he is "an ass-head, and a coxcomb, and a knave; a thin-faced knave, a gull."
William Hazlitt, a famous Romantic writer of the early 1800s, wrote charmingly of these marvelous comic characters; he was delighted by their contrasting characters. Sir Toby was sanguine, red-nosed, burly, a practical joker, and always ready for "a hair of the dog that bit him." He is a fitting opposite to Sir Andrew (pale as though he had the ague), with thin, smooth, straw-colored hair. Hazlitt was deeply amused by this wretched little nincompoop who values himself on his dancing and fencing, being quarrelsome yet chicken-hearted, boastful and yet timid in the same breath, and grotesque in every movement. Sir Andrew is a mere echo and shadow of the heroes of his admiration, born to be the sport of his associates, their puppet, and the butt of their jokes; and while he is so brainless as to think it possible he may win the love of the beautiful Olivia, he has at the same time an inward suspicion of his own stupidity which now and then comes in refreshingly: "Methinks sometimes I have no more wit than a Christian or an ordinary man has; but I am a great eater of beef, and, I believe, that does harm to my wit." He often does not understand the simplest word he hears, and he is such a mere reflex and a parrot that "I too" is, as it were, the watchword of his existence. Sir Toby sums him up in the phrase: "For Andrew, if he were opened, and you find so much blood in his liver as will clog the foot of a flea, I'll eat the rest of the anatomy."
And of Maria, Hazlitt writes: "We have a sneaking kindness for Maria and her rogueries. She fits in with Sir Toby Belch's view of the world, and it is true that this 'youngest wren of nine' and 'as pretty a piece of Eve's flesh as any in Illyria' later married him. They are both opposed to Malvolio because they represent the "cakes and ale" of which, because he was a virtuous puritan, Malvolio so disapproved.