As with each of us . . . characters in our books change as the story progresses. The growth of a character is very important. I think this aspect of writing is sometimes overlooked or even forgotten. We focus so much on what is happening externally that we forget what is happening internally.
And when you think about it - his motivation doesn’t change either. He accepts a mission, and he doesn’t stop until it’s accomplished. There are always the ‘mini’ motivation interruptions such as saving a woman from drowning or escaping a death trap.