in this scene benvolio and mercutio  were talking and benvolio had said that the Capulet are patrolling the streets. as he said that the Capulet arrived. benvolio said that they wont escape a brawl  but mercutio didnt care. as benvolio said this tybalt arrives looking for romeo . tybalt spots benvolio and meructio and started a cuss battle. this aggravated mercutio starting a fight.but  romeo arrives at the scene. then tybalt says that his beef is with romeo. romeo didnt want to fight because of the relationship with Juliet. this upsets mercutio starting a fight with tybalt. but romeo stops mercutio. as this happens tybalt stabs mercutio making him die. tybalt leaves. mercutio blames romeo on his death. tybalt then returns. romeos rage overwhelms is love killing tybalt.