Describe the changes in the wounded man's feelings for the king in "Three Questions" by Leo Tolstoy. What brought about this change?

The wounded man initially set out to kill the king to avenge his brother, who was executed by the king. From this, we can reasonably infer that the wounded man's initial feelings for the king were hostile.
However, after the king tends to the man's wounds, the wounded man exclaims that he shall serve the king as his "Most faithful slave." The implication here is that the man's feelings have changed considerably. Whereas once he hated the king, now he feels indebted to him. Whereas once he wanted to kill the king to appease his anger, now he wants to serve the king to pay back the king's kindness.
This relationship between the king and the wounded man serves to answer the king's questions. He learns that the most important man is always the man to whom one is talking at the present moment. And he learns that the most important business, or affair, is "to do that person good."