No impact on the writing but certainly plenty of impact on the story.
But do I? This question has been at the forefront of my mind for the last year.
I’ve even created two outlines, one where that 2nd main character lives, the other where they die.
Keeping the 2nd main character alive presents one timeline and of course, killing that character produces another timeline.
Both are compelling stories to write.
Unlike most authors (given what I read online) I wrote my synopsis first. From there I built the story.
And so far my synopsis is fulfilled with that other main character dying.
Argghhhh! Decisions! lol 😀