Early in the play (Act 1) Lord Capulet is illustrated as more of a doting father. He is shown to be jolly, in a good mood, and quite happy with his daughter, Juliet. This jollity is evidenced by Lord Capulet throwing a big banquet party.
He is also a fairly calm individual and shows clear, rational, patient thought. Paris asks Lord Capulet about marrying Juliet, and Lord Capulet takes it in stride. He doesn't say yes, but he also doesn't say no. He believes his daughter is too young to marry at the age of fourteen, so he suggests that Paris wait two more years. Other evidence of his calm demeanor occurs at the party. Romeo shows up and there are some of Capulet's supporters that want Romeo thrown out. Lord Capulet's response is something akin to "leave him be. He's not hurting anybody, he's well behaved, and many in the city love Romeo."
Later in act three though, Lord Capulet shows that he has become (or is at times) quick to anger. Juliet tells her father that she will not marry Paris, and Lord Capulet blows up at her. He calls her "young baggage" and "disobedient wretch." Lord Capulet thought he had found his daughter a good match and had all but assured Paris that Juliet would not have a problem with the deal.