Act 3, scene 1 is a very important scene in Romeo and Juliet. It begins the transition of the theme from romance to tragedy. With the death of Mercutio who is seen as the light hearted character in the play, and the banishment of Romeo, act 3, scene 1 starts the chain of tragedies that will end of the play. This is why this scene so crucial. We can also see in this scene that fate has a significant role to play. If it was not for certain coincidences the result of the scene may have been very different.
Before this scene we know that Romeo was seen at the Capulet's party by Tybalt. Insulted by Romeo's presence Tybalt goes to quarrel with him but is apprehended by Lord Capulet. Tybalt then seeks retribution in act 3, scene 1 for Romeo's insolence.
From the beginning of this scene we can sense that something significant is going to happen and we can sense the tension. Benvolio first senses this tension in the atmosphere and advises Mercutio to "retire";
"I pray thee, good Mercutio, let's retire:
The day is hot, the Capels are abroad,
And if we meet we shall not escape a brawl,
For now, these hot days, is the mad blood stirring."
Benvolio can see that there will be trouble and tries to avoid it, but Mercutio refuses to back down and because he does not heed Benvolio's advice they meet the Capulets, which indeed results in a "brawl." Here we also witness another coincidence in the play. Mercutio who seems to be a light-hearted character, at that time was fired up and ready for a fight. If he had listened to Benvolio, the whole incident almost certainly wouldn't have occurred. We see once again that Mercutio's eagerness to start a fight when he speaks to Tybalt for the first time in the scene:
"Tybalt: Gentlemen, good den, a word with one of you."
Mercutio: And but one word with one of us? couple it with something,
We can see Mercutio's intensions. He is trying to aggravate Tybalt into a fight. He continues with hi...