Benvolio and Mercutio are hanging out and Benvolio wants to leave so that Mercutio doesn't pick a fight with anyone, especially the Capulets.
"I pray thee, good Mercutio, let's retire. The day is hot, the Capulets abroad, And if we meet we shall no scape a brawl.
Tybalt walks in, looking for Romeo; Benvolio tells Mercutio although he does not care.
By my head, hear come the Capulets.
By my heel, I care not.
As Tybalt was looking for Romeo he fall upon Benvolio and Mercutio, he asked them if they knew where Romeo was and they started to argue.
Well, peace be with you sir. Here comes my man.
Tyblat and Mercutio started to fight an Tybalt killed Mercutio.
Good Kings of Cats, nothing but one of your nine lives. That I mean to make bold withal, and, as you shall use me hereafter, dry-beat the rest of the eight. Will you pluck you sword out of his pilcher by the ears? Make haste, lest mine be about your ears ere it be out.
I am for you.
Romeo was upset that Tyblat killed Mercutio. He may have wanted to seek revenge at the moment but...
O Romeo, Romeo, brave Mercutio's dead! That gallet spirit hath aspired the clouds, Which too untimely here did scorn the earth.
Romeo regret killing Tybalt. After everyone found out what he did, they band him from Verona.