Romeo told Tybalt to take his insult back; Tybalt called Romeo a villain.
Tybalt kills mercutio and rome kills Tybalt
Tybalt tries to start a fight with Romeo earlier in 3,1 but Romeo refuses to be drawn in. After Mercutio is fatally wounded, Tybalt is hustled away by his friends. He returns after Mercutio's death and before he has a chance to say anything, Romeo says, "Now Tybalt, take the "villain back again that late thou gavest me." Romeo is now accepting Tybalt's original challenge, not issuing a new one himself. It is Tybalt who really started the fight.
Juliet thought she saw Tybalt's ghost trying to kill Romeo, so she threw away her fears of drinking the sleeping potion. She drank it so Romeo could come and take her away. If Romeo was with her, she could save him from Tybalt's ghost. The lines (from Act 4 scene 3) are: "O, look! Methinks I see my cousin's ghost Seeking out Romeo, that did spit his body Upon a rapier's point. Stay, Tybalt, stay! Romeo, I come! This do I drink to thee."
Mercutio is woried because Tybalt is an excellent fighter
The Capulet's ball was to take place at night
Tybalt kills mercutio and rome kills Tybalt
Tybalt tries to start a fight with Romeo earlier in 3,1 but Romeo refuses to be drawn in. After Mercutio is fatally wounded, Tybalt is hustled away by his friends. He returns after Mercutio's death and before he has a chance to say anything, Romeo says, "Now Tybalt, take the "villain back again that late thou gavest me." Romeo is now accepting Tybalt's original challenge, not issuing a new one himself. It is Tybalt who really started the fight.
Nobody sent Tybalt. Tybalt sent Tybalt. Why? Because he's decided he doesn't like Romeo and Capulet stopped him from fighting at the Capulet party in Act 1 Scene 5. Tybalt has decided to take matters into his own hands by issuing the challenge.
Mercutio is looking for a fight anyway. He doesn't like Tybalt and sneers at him, calling him the "Prince of Cats". When Romeo does not respond to Tybalt's insults, Mercutio gets angry on Romeo's behalf, but it wasn't going to take much to get his sword out anyway.
Juliet thought she saw Tybalt's ghost trying to kill Romeo, so she threw away her fears of drinking the sleeping potion. She drank it so Romeo could come and take her away. If Romeo was with her, she could save him from Tybalt's ghost. The lines (from Act 4 scene 3) are: "O, look! Methinks I see my cousin's ghost Seeking out Romeo, that did spit his body Upon a rapier's point. Stay, Tybalt, stay! Romeo, I come! This do I drink to thee."
His name is Mercutio. Mercutio is a friend of Romeo's and a relative of the Prince's. He does not exactly take Romeo's place in a fight: Tybalt wants to have a fight with Romeo but Romeo refuses to fight him. Mercutio, who has been taunting Tybalt right along, thinks it a shame that there is to be no fight and is disappointed in Romeo for refusing to take part, so he challenges Tybalt himself.
Mercutio is woried because Tybalt is an excellent fighter
The Capulet's ball was to take place at night
There was a fight between him and Tybalt and Romeo got in the middle to stop Mercutio and take him home. But, Tybalt's sword goes under romeo's arm and stabs Mercutio. Basically, Mercutio gets stab by Tybalt.
Lady Capulet wants to take revenge on Romeo because he killed Tybalt, her nephew, in a duel. She is grief-stricken and desires justice for her family's loss, leading her to seek retribution against Romeo.
Romeo does not want to fight Tybalt because he has just married Tybalt's cousin Juliet. So this means they are related and Romeo does not want to harm him. Also to start a fight with a Capulet (because Romeo is a Montague) would have Romeo banished. Romeo does not want to be banished or upset his wife, Juliet, by killing her cousin.
Tybalt calls him a "villain". Normally this would be enough for Romeo to start a fight with him. However, Romeo calmly replies that although Tybalt may not know the reason why Romeo is not going to take offence to that word, it is enough that he knows that the reason exists. He continues, "Villain am I none. I see you know me not."