Throughout the course of the play Lord Capulet goes from calm reasoning to spontaneous anger to contrition.
Lord Capulet is Juliet’s father. In the beginning of the play, he is in a good mood. He is throwing a big party to show his beautiful daughter off, though he tells Paris she is too young to marry at fourteen.
But now, my lord, what say you to my suit?
But saying o'er what I have said before:
My child is yet a stranger in the world;
She hath not seen the change of fourteen years,
Let two more summers wither in their pride,
Ere we may think her ripe to be a bride.
When he comes across the brawl, he is ready to jump in. Capulet’s willingness to join the fray, despite his age and status, demonstrates his exuberance, spontaneity, and passion.
My sword, I say! Old Montague is come
And flourishes his blade in spite of me. (Act 1, Scene 1, p. 12)
The prince describes him as “old” and clearly asserts that Lord's Capulet and Montague are responsible for the original quarrel.
Three civil brawls, bred of an airy word,
By thee, old Capulet, and Montague,
Have thrice disturb'd the quiet of our streets,
To wield old partisans, in hands as old,
During the party, we see another side of Capulet. After the Prince's reprimand that he control his household, he is actually quite reasonable about Romeo’s attendance at the party. Tybalt wants to cause a scene, but Capulet holds him back.
Content thee, gentle coz, let him alone.
He bears him like a portly gentleman,
And, to say truth, Verona brags of him (70)
To be a virtuous and well-govern'd youth (Act 1, Scene 5)
This is one of the most ennobled things Capulet says in the play, demonstrating that he is not unloving, as he may appear to be in other parts, especially when his daughter tells him she does not want to marry Paris.
Hang thee, young baggage! disobedient wretch!
I tell thee what—get thee to church a Thursday (165)
Or never after look me in the face.
Speak not, reply not, do not answer me! (Act 3, Scene 5)
Capulet’s anger at Juliet’s defiance stems both from his pride (he assured Paris that he "doubted not" Juliet would agree with him) and his frustration (he thinks he has made a good match for her). In his mind, he is shocked and surprised.
It is not until he discovers his daughter’s death that he begins to feel contrite. He feels bad because he forced her into marrying in secret and into killing herself. He is grieving and guilt-ridden and decides to end the feud in her honor.
O brother Montague, give me thy hand.
This is my daughter's jointure, for no more
Can I demand. (Act 5, Scene 3)
In the end, Capulet forgives Montague and agrees to let Romeo be buried in the Capulet tomb with his daughter. He has reformed, having lost his only daughter. It took that to help him realize what he had.
Capulet does show a progression throughout the play. By the end of the play, he has paid the greatest consequence for his folly with Montague and he realizes this too late.