Tybalt attacks Mercutio because Mercutio challenges him: "Tybalt, you ratcatcher, will you walk?" Tybalt tries to get Romeo to fight him, but Romeo refuses because of Juliet, saying that he "love[s] thee [Tybalt] better than thou canst devise." He won't attack Juliet's cousin. But Mercutio doesn't approve of Romeo's actions, calling them "o calm, dishonorable, vile submission!" Tybalt hesitates but ultimately decides to fight Mercutio, leading to the sequence of events in which Romeo kills Tybalt. We don't know what would have happened if Mercutio hadn't challenged Tybalt. Would Tybalt have attacked Romeo in cold blood? Or would Romeo have managed to persuade Tybalt not to fight? Might Romeo and Juliet have had a chance at a happy ending? We'll never know. In most of Shakespeare's tragedies, there is a moment at which everything goes wrong and the tragic end becomes inevitable, and this is that moment for Romeo and Juliet. Up until this point, the play might have seemed to be a comedy to its first viewers, starring as it does two lovers whose families oppose their match. After the first violent death, though, the audience would have known for sure that they were looking at a tragedy.

Though Tybalt's quarrel is with Romeo, he begins the momentous duel in Act 3 by fighting with and killing Mercutio instead. Tybalt ultimately attacks Mercutio because the garrulous and hot-headed character insults Tybalt and goads him into a duel to protect Romeo's honor.

From the beginning of the encounter in Act 3, Scene 1, it's clear that Mercutio is itching for a fight. For instance, when Tybalt signals that he wants to talk to Mercutio and Benvolio, Mercutio responds "And but one word with one of us?/ Couple it with something; make it a word and a blow" (38-9). Basically, Mercutio is egging Tybalt on in an effort to induce him to fight. Tybalt ignores Mercutio's attempts until Romeo joins the scene and refuses to fight. Upset with Romeo's pacifism, Mercutio unleashes a heap of insults on Tybalt, calling him "rat-catcher" (73) and "Good King of Cats" (75) and saying "Will you pluck your/ sword out of his pilcher by the ears? Make/ haste, lest mine be about your ears ere it be out" (77-9). In short, Mercutio deliberately goads Tybalt into a duel by insulting him venomously. It is not until Tybalt kills Mercutio that Romeo is driven to draw his own sword.  

Why did Tybalt kill Mercutio in Shakespeare's Romeo and Juliet?

In Act III, Scene 1 of William Shakespeare’s The Tragedy of Romeo and Juliet, Romeo’s closest friend, Mercutio, is killed by Tybalt, Juliet’s cousin and a young man of extremely violent disposition. Romeo, in whose arms his friend utters his least breath, subsequently kills Tybalt. The tragic encounter between partisans of the two warring clans in Shakespeare’s play is not unexpected given the build-up to some form of climatic confrontation from the play’s opening scenes. Romeo and Juliet is about the love of two young people whose families have been feuding for years, to the consternation of the town’s reigning monarch, Prince Escalus. That feud permeates the atmosphere in which Romeo and Juliet takes place, evident in the play’s opening scene. The play opens with two representatives of the Capulets determined to attack and vanquish any Montagues unfortunate enough to cross their path. The discussion between these two partisans provides the context in which the scenes and eventual tragedies that follow occur:

GREGORY The quarrel is between our masters and us
their men.
SAMPSON ’Tis all one. I will show myself a tyrant.
When I have fought with the men, I will be civil
with the maids; I will cut off their heads.

The violent sentiments evident in this discussion illustrate the depth of hatred dividing the Montagues and Capulets. It will only be with the eventual deaths of the titular characters that the clans’ respective leaders come to appreciate the insanity that has defined their relationships.

Why, then, did Tybalt kill Mercutio? Because Tybalt, as noted, is a violent, temperamental individual and a fierce partisan in the feud. Note, in the following challenge from that opening scene, Tybalt’s antipathy towards the Montagues:

What, drawn and talk of peace? I hate the word
As I hate hell, all Montagues, and thee.

By the time the action of Act III takes place, the stage has been well-established for a fatal confrontation between members of the two clans. Tybalt kills Mercutio because Mercutio is a Montague close to Romeo. The two are sworn enemies, although Mercutio is slower to violence than Tybalt, who is always prepared to kill, as he does with respect to Romeo’s dear friend.

Why did Tybalt kill Mercutio in Shakespeare's Romeo and Juliet?

Tybalt's quarrel is with Romeo because Romeo crashed the Capulets' party the night before. He wants to fight Romeo to defend his family's honor. However, Romeo is not there with his friends, Mercutio and Benvolio, and when Tybalt speaks to Mercutio, Mercutio gets offended by Tybalt's mocking speech and threatens him. He points to his sword, saying, "here's my fiddlestick. Here's that shall make you dance," implying that he will attack Tybalt with his weapon. When Romeo arrives on the scene, Tybalt withdraws from conversation with Mercutio and challenges Romeo. However, Mercutio's all riled-up, so when Romeo refuses to fight Tybalt (his relative by marriage now that he's secretly wedded Juliet), Mercutio considers it a "dishonourable, vile submission." Mercutio attacks Tybalt, and they fight. When Romeo steps between them to stop the confrontation, Tybalt stabs Mercutio under Romeo's arm. Thus, Tybalt kills Mercutio, probably for a few reasons: first, he is Romeo, his enemy's, friend. Second, Mercutio himself does come at Tybalt with his sword. Third, Tybalt is incredibly proud and will not allow such a challenge to go unmet.

Why did Tybalt kill Mercutio in Shakespeare's Romeo and Juliet?

The answer to this question can be found in Act III, Scene 1 of Romeo and Juliet. Tybalt, a Capulet, was not looking for a fight with Mercutio, who is Romeo's friend and not a Montague. Tybalt is searching for Romeo when he encounters Mercutio and Benvolio. When Romeo arrives, Tybalt says "peace be with you" to Mercutio, who has repeatedly tried to goad him into a duel by insulting and challenging him. When Romeo refuses to fight Tybalt, Mercutio steps in and offers a direct challenge that Tybalt cannot refuse with honor. He seems to be holding his own with Tybalt (who he has previously characterized as a master duelist) until Romeo steps in and attempts to restrain him. When he does this, Tybalt runs Mercutio through, giving him a mortal wound. This is a pivotal event because Romeo responds by fighting with Tybalt when he returns. He kills Tybalt, and is banished as a result. This begins the chain of events that lead to his and Juliet's tragic end.

Why did Tybalt kill Mercutio in Shakespeare's Romeo and Juliet?

In William Shakespeare's Romeo and Juliet, Tybalt is a "kinsman of old Capulet," while Mercutio is one of Romeo's kinsmen and his friends. In the opening scene of Act III, Mercutio and Benvolio (another of Romeo's friends) are out in Verona when they encounter some of the Capulets.

Tybalt wants to talk to the pair, but Mercutio immediately begins with a hostile tone saying, "make it a word and a blow." Romeo comes upon the group and the hostilities escalate. Tybalt soon challenges Romeo to "turn and draw". Romeo, however, does not want to fight with Tybalt. Mercutio, though, does resume a hostile posture and swordplay breaks out between the two despite Romeo's efforts to stop it. In the confusion, Tybalt stabs Mercutio under Romeo's arm ("I was hurt under your arm").

So, it would appear that Tybalt kills Mercutio because Mercutio had acted in a hostile manner toward him and because Tybalt and Mercutio were on opposite sides of the war between the Capulets and the Montagues.

Why did Tybalt kill Mercutio in Shakespeare's Romeo and Juliet?

I think it is important to remember that Tybalt's complaint is with Romeo and not with Mercutio. Remember that Tybalt was upset with Romeo's presence at the Capulet part; it was Mercutio who actually had a legitimate invitation.

In fact, when Tybalt confronts Mercutio (Act III, scene i) it is only to determine the whereabouts of Romeo. When Romeo appears, Tybalt stands down against Mercutio with the line: "Well, peace be with you, sir: here comes my man."

It is Mercutio, then, who continues to provoke Tybalt, particularly because Romeo refuses to fight. Romeo then comes between Mercutio and Tybalt in hopes of separating them. It is at this moment that Mercutio receives his fatal wound. It is not intentional on the part of Tybalt; it happens only because Romeo is in the way.

It could be argued that Romeo is as much to blame for Mercutio's death as is Tybalt.

Why did Tybalt kill Mercutio in Shakespeare's Romeo and Juliet?

In the play "Romeo and Juliet" by William Shakespeare, the author show us, in Act 3 Scene 1 how Mercutio teases Benvolio, and then tries to mock and humiliate Mercutio. Mercutio usually is up for anything that looks like a bit of fun - he is quite a disruptive character who likes to get attention. But Tybalt won't be distracted and is determined to get Romeo to duel with him. From their past history, this is probably in fun and competition at first. Romeo, floating on cloud nine from love of Juliet and good will to all his new kin, isn't interested. So Mercutio draws his sword and in the ensuing fight both Mercutio and Tybalt get killed. Things have gone too far, and when they get out of control people get killed in the fallout, not necessarily from a prime motive for murder.

Why did Tybalt kill Mercutio in Shakespeare's Romeo and Juliet?

I think Tybalt killed Mercutio as a result of not being able to get Romeo fired up for a fight.

Tybalt was upset that Romeo trespassed at the party. So, he went and found the guys but Romeo wasn't there yet. He and Mercutio have a war of words and then Romeo walks up. Tybalt tries to engage Romeo in a fight, but Romeo is happy to just let Tybalt take him out. Mercutio can't stand watching his friend Romeo just give up, so he gets involved. He and Tybalt end up fighting. Romeo tries to break them up and Tybalt takes a cheap shot while Romeo is in between them. I think Mercutio provoked the fight, but Tybalt shows how cold-hearted he is by not fighting fair. A villian will take advantage of a situation like that and I think you now have more reason to point the finger at him.

Why did Tybalt kill Mercutio in Shakespeare's Romeo and Juliet?

In my opinion, Tybalt kills Mercutio because he is a complete hothead.  Tybalt really hates the Montagues and wants to fight them at every turn.

Think about what he has already said and done in the play up to this point.  At the start of the play, he wants to fight Benvolio when Benvolio is trying to break up the fight between the two families' servants.  Then, later on in Act I, Lord Capulet has to stop him from attacking Romeo.  He wants to attack Romeo when he sees him at the Capulets' party.

So from this you can see that he is really quick tempered and always looking for a fight, at least with anyone who is a Montague.