Romeo enters the scene with Mercutio and Tybalt. Tybalt is angered at Romeo and calls him a villain. Romeo forgives Tybalt's anger because he has reason to love him.
Tybalt, the reason that I have to love thee doth much excuse the appertaining rage to such a greeting. Villain am I none. Therefore farewell. I see thou knowst me not.
Romeo, the love I bear thee can afford no better term than this: thou art a villain.
Tybalt is offended at what Romeo has said and says for Romeo to draw his sword to fight. Romeo stays calm and protests as he doesn't want to fight.
I do protest I never injured thee, but love thee better than thou canst devise till thou shalt know the reason of my love; and so good Capulet, which name I tender as dearly as mine own, be satisfied.
Boy, this shall not excuse the injuries that thou hast done me; therefore turn and draw.
Mercutio misunderstood Romeo's calm response and assumes that Romeo is afraid to fight and draws his sword to fight Tybalt for Romeo.
O calm, dishonorable, vile submission! Alla stoccata carries it away
Tybalt stabs Mercutio and flees. Mercutio plays it off as a scratch but soon dies.
Romeo angered about the death of Mercutio finds Tybalt and says that either he or Tybalt shall die for Mercutio. Romeo starts to duel him.
That late thou gavest me, for Mercutio's soul is but a little way above our heads, staying for thine to keep him company. Either thou or I, or both, must go with him.
Thou, wretched boy, that didst consort him here, shalt with him hence.
Romeo kills Tybalt in the name of Mercutio. Romeo then flees the scene so he isn't caught and be sent to death by the Prince.