Tybalt is the cousin to Juliet Capulet. Tybalt's appearance is immediate, as he first debuts in Act 1 Scene 1. He is a man with a fiery temper and a passionate member of the Capulet house. Tybalt is very protective of Juliet's honor and is very insistent on the "rules" of the feud, as in, no house can meddle in any other house. In his first appearance, he is very open about his hate towards the Montagues, saying that he hates Benvolio as much as he hates hell. The next appearance he has is at the Capulet masquerade party, when he is enjoying the party when he notices Romeo. Tybalt is immediately enraged, feeling as if Romeo is mocking and scorning their festivities. He goes to get his sword, but Lord Capulet stops him, telling Tybalt that even though Romeo is a Montague, he's still a fine young man, and that he didn't want there to be a big quarrel in his house. Tybalt is upset by his Uncle's "cowardice", and he vows that he will get revenge on Romeo for this.
In 3.1, Tybalt approaches Mercutio and Benvolio, saying that he was looking for Romeo and that he knew to ask them because they consort with him. Mercutio gets very mad at this. Romeo arrives, and Tybalt immediately wants to fight with him. However, Romeo tells Tybalt that he has more reason to love than to hate him -- mainly because Romeo (unbeknownst to Tybalt) had just married Juliet, and he now considered Tybalt to be his kinsman. When Romeo refuses to fight him, Mercutio decides to take his place, being thoroughly annoyed by Tybalt's presence. To Benvolio and Romeo's dismay, the two begin their duel. Romeo tries to break up the fight, but Tybalt, aiming for Romeo, stabs Mercutio underneath Romeo's arm on accident, causing Mercutio's death. Horrified that he killed the wrong man, Tybalt flees with the rest of the Capulet party. Romeo, being devastated at this turn of events, takes his sword and goes after Tybalt. Tybalt is killed by Romeo in their subsequent duel.
"Turn thee, Benvolio, look upon thy death." 1.
"What, drawn, and talk of peace! I hate the word, As I hate hell, all Montagues, and thee." 1.1
"Tis he, that villain Romeo." 1.5
"It fits, when such a villain is a guest: I'll not endure him." 1.5
"Well, peace be with you, sir: here comes my man." 3.1
"Romeo, the hate I bear thee can afford No better term than this,—thou art a villain." 3.1
"Boy, this shall not excuse the injuries That thou hast done me; therefore turn and draw." 3.1
"Thou, wretched boy, that didst consort him here, shalt with him hence." 3.1 (his last words)