In Shakespeare's Romeo and Juliet, Tybalt is a flat character, who consistently exhibits a nature that is belligerent, resentful, and obstinate. His first appearance in the play is in the opening fight scene in which he challenges Benvolio:
What, art thou drawn among these heartless hinds?
Turn thee, Benvolio, look upon thy death. (I,i,65-66)
Death remains on his mind with regard to the Montagues throughout the play. When Tybalt espies Romeo in the Capulet house he wishes to kill him immediately, but is restrained by his uncle, Lord Capulet, who calls him a "princox" (I,v,91)
Even the hot-tempered character, Tybalt is ready to dual when he encounters Mercutio in Act III. On such a hot day in Verona, unfortunately, Mercutio, too, is angry with the "Prince of Cats" as he has named Tybalt. And, ironically, it is Mercutio who challenges Tybalt. But, unlike Mercutio, Tybalt is not above taking unfair advantage of Mercutio as he reaches around the intervening Romeo and slays Mercutio.
Like his name, Mercutio has a changeable nature. Whereas he has been bawdy and jovial in the two previous acts, Mercutio displays much cholera in the third act, showing eagerness to fight a Capulet, and in this way he is much like Tybalt. At his end, his bitterness overcomes his loyalty as he dies:
A plague be o' both your houses (III,i,99)
Before the third act, Mercutio seems much unlike Tybalt. He is playful, tossing bawdy jokes at the nurse, urging Romeo to reveal himself in Act II with such quips, and entertaining his friends with his eloquent monologues. He is the center of attention whenever he is around unlike Tybalt who sulks in the background. Nevertheless, the two characters both seem too extreme to be able to last without tragedy.