The protagonist in your book is there to be the hero (presumably). The protagonist will go through the plot, being sure to grow along the way, and save the world. That is the protagonist’s purpose and the character will probably come to terms with that along the way.
What about the protagonist’s dreams, though? Sure, perhaps they dream of the world being safe or of the Bad Guy reforming, but what did they dream about before being thrust into the hero role?
What your protagonist has always dreamed for themselves will shape the way they carry themselves — body, mind, and soul — throughout the story. Will the dream change along with them as the plot goes further along? Will the dream steadfastly stay in their heart for when everything is all over, to keep that simple hint of normalcy in their lives, even if the plot has made everything change forever?
Which is the better ending, for a protagonist’s dreams to grow with them or to stay the same as they were before the protagonist’s journey, no matter how bittersweet it may have become?
I’ll admit, I personally haven’t given much thought to some of my protagonist’s dreams outside of the plot of their story. It’s something that I want to work on, something that I want to explore about their psyches. What dreams will be put on hold for the plot? Will those dreams be waiting when the plot is done?
More importantly, will the protagonists recognize their old dreams when the plot is over?