I'm writing this fantasy novel in a setting during the beginnings of an industrial revolution. The main protagonist is your typical good-hearted guy who wants to be a soldier to save and protect people but really hasn't internalized the fact his dream would put him in the path of harming others, which he can't really bring himself to do.
However, while commonly that would result in him fighting to keep his moral and ideals, the plot would force him to eventually kill some of his opponents, whom simply can't be reasoned.
On the either side, the co-protagonist of the story has a more rough and seemingly cold-hearted personality and when put against some people trying to harm her, she didn't hesitate a second to kill them, to the point the MC was wary of her for a while.
Of course, beyond the uncaring exterior, she was affected by what she did, even if she didn't show it. She just has this frame of mind when she acts ruthlessly and does what she must to protect herself and the few people she cares about.
Like, she isn't a totally good person, but she isn't totally malignant either. She is just grey.
Problem is, while I'm adding this vulnerability to her so people can try to understand where she is coming from, I wonder if it's enough. I don't want people to hate her or feel upset about the whole thing, thinking she is corrupting the other protagonist or something like that.
The story world is simply not one where you can amend everything in a peaceful way.
What would you recommend me to get a balance, or getting people to empathize with both protagonists despite how opposite they are, and how dislikable the second one may seem at first?