A number of characters contribute to Romeo’s banishment. Tybalt intends to challenge Romeo for attending a Capulet party. He instigates a number of fights, telling Benvolio in the first scene, “What, drawn, and talk of peace! I hate the word, / As I hate hell, all Montagues, and thee.” Mercutio is another hot-headed individual who gladly reciprocates Tybalt’s aggression. In spite of Benvolio’s pleas for peace, Mercutio draws and fights Tybalt after exchanging insults. Romeo attempts to control this brawl, inadvertently causing Tybalt to stab Mercutio. The death of his friend spurs Romeo to attack and kill Tybalt.
Characters in the play disagree as to who carries the blame for these deaths. Benvolio reports Romeo’s initial reluctance to fight as well as Tybalt and Mercutio’s eagerness. Lady Capulet entirely blames Romeo for his actions, but Lord Montague defends Romeo as a mere deliverer of justice: “His fault concludes but what the law should end, / The life of Tybalt.” The penalty for murder and fighting in the streets is death, so Romeo simply followed the law by executing Tybalt after he had stabbed Mercutio.
The prince is furious (partially because Mercutio was a kinsman), and he decides to fall somewhere in the middle: he exiles but does not execute Romeo, unless he returns. Tybalt started a fight, Mercutio took him up on it, Romeo killed Tybalt in revenge, and the prince punished Romeo with banishment. Therefore, Tybalt, Mercutio, Romeo, and the prince all play an important role in Romeo’s exile. The two people who may have the most to do with it, however, are Capulet and Montague, the two patriarchs who perpetuates the feud that led to all the violence in the first place.