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.