I'll admit, at first I had to do a double take at this thread but I think the question you're asking is weather your investment with certain characters effects you're initial plans with your story. I think that's what you're asking about since our characters aren't real (as in their destinies are controlled by us the writers)
In the 7 plus years I've been working on my comic, from the moment I started brainstorming it to now, I've noticed that my investment in certain characters has effected the plans for a story I wanted to tell, leading me to change things or reconsider story telling decisions. For example, the father of my comic's main character (who was originally supposed to be dead following the dead parents Shonen trope but had him be around in the MCs life, although I think that decision had less to do with attachment) was originally going to be a nothing character but as the years have gone and I've brainstormed his backstory in my mind, I saw a lot more potential for him. Rather than being a typical, mentor/generic father figure, I felt like there was more to his character than that. As a man who's not the invisible father kids imagine their dads being, but as someone who feels like they're not good enough for their kids, partially influenced by the loss of the mc's mother and his wife. While not being a main character, I saw him as someone who could go through a character arc where he gains that confidence in himself and is able to come to terms with the death of his wife after so many years. The wife's and the mc's mom's death is also something I reconsidered at some point, especially after I drew some au art where she hadnt died. It really hit me emotionally as it reminded me of when my own mother was alive (she died of cancer when I was 12), and made me wondering if I could revive her in someway later down the line. And as much as I would gladly do that, as a writer I felt like it would cheapen or ruin the story if I brought her back from the dead. I think for that, I'll probably write some au where she is alive in order to avoid ruining the main storyline.
Not to mention characters who were supposed not have active combative roles gaining said roles as my series' plans have had more time to cook. But I think that's a story for another day