Greetings, @samdove.

Perhaps the protagonist was very confused at the beginning of the story and was able to hatch a plan to harm the good king who gave him his trust.
When he thought of the innocent people he would harm with his plan, he came to his senses and acted honestly. It is hard to think that humans have such abrupt changes, also that the king would place his trust in him again.
You may want to consider some resources to devise your stories. For example, we have tips on developing characters
Thanks for commenting on other stories posted in the community.