You might like to consider the character of Pedro in Chapter Thirteen ad how he takes responsibility for his own actions and failures in the way in which he did not warn Ultima about Tenorio in the same way that Narciso did. Note how Pedro responds to his nephew's question:
My uncle started to answer, but held back. I saw his hands grip the steering wheel so hard that his knuckles turned white. For a long time he fidgeted, then he finally said, "It does not decrease my shame to say I was a coward last night. We all were. We took our father's wish as an excse. Believe me, my faith is bound with that woman for saivng Lucas. The next time, and God grant there isn't a next time, I will not shirk my duty to her."
I think this is an important example of responsibility because we see here that Pedro, in spite of his initial reactions of shame and embarrassment, indicated in the tight grip he places on the steering wheel, does not shirk from admitting his own mistakes, acknowledging them openly and taking responsibility for them, and determines to learn from his mistakes and be faithful to Ultima in future. This is an excellent example to focus on because Pedro ignores his urges to deny his cowardice and lack of responsibility, and admits his faults, determining to improve his character in the future.