I know this seems like a weird question, but this became a problem when planning my story, and I'm not sure how to solve it.
I have a plot point where one girl figures out that a close friend is actually her stepsister (her long-lost dad marries her friend's mom). There are two people that would be fit, but I'm not sure who should be the stepsister. Character A is logically the best choice, as her personality has a lot of potential for conflict (Character A doesn't trust easy and isn't very open, so getting used to a new sister may be hard). However, when I let my imagination dictate what happens instead of thinking of the best option, Character B tends to be the girl's stepsister. While there is the potential for conflict, it's not as clear as Character A. Both options are possible and won't create a plot hole.
Should I go with the idea that makes more sense logically? Or would it be best if I go with how I imagine it instead?
Source: reddit post