In this fourth chapter we have two stories with a different view as to what it took to believe in Jesus. In the case of the Samaritan woman, it took Jesus telling her the abbreviated version of her life story. In the case of the ruler, it took Jesus telling him that his son would live.
In the first case, Jesus, culturally, should not have been spending time with her. She was a woman and a Samaritan (whom the Jewish people of the day despised) and was living with a man who wasn't her husband. Yet Jesus went out of his way to have a conversation with her and to meet her where she was.
In the second case, the Jewish leader sought out Jesus. He asked for help healing his son. Jesus helped, but he did not go anywhere to do it. He simply sent the father back home and the father learned on the way that his son had recovered. In this case, culturally, Jesus should have gone out of his way to help--but he didn't. That honor was reserved for a despised woman who didn't seek him out.
I think this is valuable to think about as we think about how God interacts with people. There isn't a single model of interaction. There isn't a pattern based on cultural norms. God chooses the rules, and sometimes the results are quite unexpected.