In act 1, scene 5 of Romeo and Juliet, Tybalt reacts to Romeo's voice by calling immediately for his sword. He is furious to find a Montague at the feast, and his first thought is of physical violence, even to the point of murder. He believes that the only reason a Montague could have come to a Capulet feast is to "fleer and scorn at our solemnity," in other words, to mock and disrupt the occasion.

Capulet's response is initially peaceful and even generous to Romeo, of whom he remarks:

He bears him like a portly gentleman;
And, to say truth, Verona brags of him
To be a virtuous and well-govern'd youth:
I would not for the wealth of all the town
Here in my house do him disparagement.

There are several points of interest here. One is the confirmation of the idea in the prologue that the feud between the Capulets and the Montagues has lately progressed from "ancient grudge" to "new mutiny." Capulet does not much care about the feud, and it seems that he and his generation may be inclined to forget all about it. It is Tybalt, a young man, who is determined to keep the feud alive.

Another striking feature of this scene is the insight it gives into the character of Capulet, which sheds light on his later treatment of Juliet. Capulet is generous and genial as long as he is not crossed. He speaks affectionately to Tybalt and is full of praise for Romeo. However, as soon as Tybalt threatens to disobey him, his manner changes entirely, and he quickly puts the younger man in his place.

In Act I, Scene 5 of Romeo and Juliet, Tybalt is enraged by Romeo's presence at the party at which Romeo falls in love at first sight with Juliet. Tybalt says:

Tybalt is terribly angered by Romeo's presence. Tybalt calls Romeo the enemy and is so angered that he wishes to kill him, adding that he would not feel remorse if he did.

Lord Capulet does not agree with Tybalt. Lord Capulet thinks of Romeo as a gentleman, someone who is virtuous and respectable. He will not allow Romeo to be disrespected in his house and tells Tybalt to ignore Romeo and calm down and improve his mood.

Tybalt, standing true to his character, reacts very violently to the knowledge of Romeo's presence while Lord Capulet actually defends Romeo (simply because Capulet doesn't want his party disrupted).  Tybalt's violence can be seen almost immediately in that he asks for his rapier and says, "Now, by the stock and honor of my kin, / To strike him dead I hold it not a sin."  Lord Capulet approaches the subject delicately with Tybalt by simply telling Tybalt to "let him alone."  Ironically, Lord Capulet then begins defending Romeo by saying, "Verona brags of him / To be a virtuous and well-governed youth.  I would not for the wealth of all this town / Here in my house do him disparagement."  Lord Capulet tries again to stop Tybalt peacefully by saying, "Therefore be patient, take no note of him."  Of course, Lord Capulet has to descend into violence himself (with his own kinsman) mostly as a result of Tybalt not respecting his will.  "He shall be endured. . . . Am I the master here, or you? Go to! . . . You'll make a mutiny among my guests!"  In this way, Romeo is left alone to ogle over Juliet at the party.