Cupid, the god of love, could have used his power to manipulate Tybalt's feelings towards Romeo by causing Tybalt to believe that Romeo had wronged him in some way or by making Tybalt feel threatened by Romeo's presence. Through subtle influences, Cupid could have planted seeds of animosity or envy in Tybalt's heart, leading to hatred towards Romeo.
Cupid could have caused Tybalt to fall in love with someone else, leading him to feel betrayed and angry towards Romeo for interfering. Additionally, Cupid could have manipulated Tybalt's emotions to make him see Romeo as a rival for attention or affection, further fueling his hatred.
Tybalt has vowed revenge upon Romeo and has sent a challenge to Romeo's father's house.
Well, if Romeo had never let Tybalt find out he was at he party (he was the only one seen by Tybalt), Tybalt would never have challenged Romeo to a fight, and the whole street brawl would never have happened. If Romeo had answered Tybalt's challenge, Mercutio wouldn't have died protecting his honor. If Romeo had so much as asked why Tybalt insulted him like that, Mercutio wouldn't have felt the need to defend his friend's honor. Then there's always not stepping in the damned fight and just let Mercutio get his anger out...So all in all, it's pretty much Romeo's fault Mercutio had died.
He says that Tybalt came after Romeo but Romeo "spoke him fair", so he then went after Mercutio, and killed him when Romeo was trying to restrain him. He says Tybalt then fled, "but by and by comes back to Romeo" whereupon Romeo killed him, Benvolio being unable to prevent it. This is mostly true, although he withholds the fact that Mercutio went out of his way to start a fight with Tybalt, who had no interest in fighting him. What Tybalt would have done to Romeo had Mercutio not been there is a director's call. The play is clear that in fact Tybalt did seek Romeo out after Mercutio's death, so Romeo was acting in self-defence in fighting him. Tybalt re-enters and Benvolio says "Here comes the furious Tybalt back again." In most movie versions, it is Romeo who chases after Tybalt, which would make this part of Benvolio's account of the fight inaccurate also.
Boy, this shall nor excuse the injuries That thou hast done me, therefore turn and draw.
No he did not. Mercutio answers Tybalt's challenge to Romeo. They begin having a sword fight. Then Tybalt attempts to stab Romeo but his sword goes under Romeo's arm and fatally wounds Mercutio. Another Answer: There is no direct indication of Tybalts intentions in the script. It simply reads, "Tybalt under Romeo's arm thrusts Mercutio in." So, whether Tybalt intended to stab Romeo or Mercutio is up for interpretation. Some directors stage Tybalt's thrust as an accident resulting from harmless swordplay.
Tybalt
It is actually Tybalt who informs Lord Capulet of the unwanted guest. Tybalt wants to kill him but Lord Capulet orders him not to make a scene at the party because, despite there enmity, Romeo is well liked in the community and it would tarnish his reputation.
Mercutio and Benvolio are discussing the hot day and the possibility of a quarrel. Tybalt enters looking for Romeo and rudely addresses them. Mercutio and Tybalt are about to fight when Romeo enters. Romeo tries to avoid the conflict because he is now married to a Capulet. Mercutio cannot stand Romeo submitting to Tybalt's cruelty and draws his sword to fight. Romeo and Benvolio try to stop the fight. Tybalt stabs Mercutio under Romeo's arm and leaves. Mercutio ends up dying. Romeo realizes his love for Juliet has made him soft and now seeks revenge. Tybalt returns and they fight. Romeo kills Tybalt and then flees after reflecting on what he has done.
Romeo killed Tybalt because Tybalt killed Mercutio. He made the decision without thinking about the consequences in regard to his relationship with Juliet. Had he deliberated more, he may not have done it, because the act of revenge would inevitably tear him away from his love because of the decree the prince made regarding the conflict between the Montagues and the Capulets.
Mercutio has no quarrel with Mercutio. He's looking for Romeo. He starts by greeting Mercutio and Benvolio very politely "Gentlemen, good-den. A word with one of you." What he wants is to find out where Romeo is so he can fight him. He starts by saying "Mercutio, thou consortest with Romeo". A "consort" is a companion, a friend, one who goes along with you; to consort with someone is to be their friend and companion, to go along with them. Tybalt's next line would be "Can you tell me where he is?" Because Mercutio is in an obnoxious mood, he manages to turn this perfectly polite statement into an insult, then to make a punning threat based on it. By the time he's done, Romeo has shown up, so Tybalt does not have to deal any further with Mercutio. He says, with great relief no doubt, "Well, peace be with you sir. Here comes my man." But Mercutio is not done with Tybalt. Not liking Romeo's placating responses to Tybalt's attempts to get him into a fight, Mercutio bursts in and calls Tybalt a "ratcatcher". Tybalt again replies politely: "What would you have with me." He only draws in response to Mercutio pulling out his own sword. What all this shows is that Mercutio goes way out of his way to provoke Tybalt into a fight he didn't want. Then when it turns out badly for him, he blames Romeo. A plague on Mercutio's house!
In Act I Scene 4 he gets Romeo to forget about his misgivings about attending the party. Otherwise, amusing as he is, he does not really influence Romeo and Romeo does not let him into his confidence. Mercutio's actions in unnecessarily fighting Tybalt, and then placing the blame on Romeo and everyone but himself when it goes wrong does have an effect on Romeo, who temporarily and under the influence of grief and anger, forgets the reason he refused to fight Tybalt in the first place. Whether he would have done so even if Mercutio had not blamed him is an open question.