Any of the supporting characters are the ML.
Why?
She is an OC in a story she hasn’t already yet. Hence she is officially in a fan fiction only this one is ‘conveniently’ a choose your character one since it has ‘yet’ to be written in stone and as a reader I have yet to choose a ML the ssystem is just a destructions for drama.
So as an OC she has to choose which one she wants to be ML.
So there ( ̄ε(# ̄)Σ