1.2: Tybalt enters the stage during fight between the servants of the Capulets and Montagues. Benvolio, a friend of the Montagues, is trying to stop the fight. Instead, Tybalt starts fighting with Benvolio. The situation gets so out of control that the Prince of Verona arrives to break it up.
1.5: Tybalt spots Romeo at a Capulet party. Furious at this invasion of Capulet territory, he wants to fight with Romeo right then and there. Lord Capulet intervenes before Tybalt can do anything and angrily orders him not to ruin the party. Tybalt has to obey Lord Capulet, but he swears to punish Romeo at the earliest opportunity.
3.1: Tybalt looks for Romeo and finds Benvolio and Mercutio. He trades some insults with them before Romeo shows up. Tybalt purposely tries to provoke Romeo into a fight. Romeo responds mildly to his abuse and refuses to fight. Mercutio challenges Tybalt to a duel instead. Romeo tries to stop them from fighting, and Tybalt wounds Mercutio while he is distracted by Romeo's interference. When Mercutio falls, seriously wounded, Tybalt exits. But he comes back in time for Romeo to challenge him to a duel to avenge Mercutio's death. Romeo kills Tybalt.