How come all or maybe most of the character of the author is nicolas? Hahah

Nicolas is the authors main character, he's featured in multiple alternate universes. the author had a whole twitter space about it a few years ago where they talked about having one main character that is the center point of all their stories. almost none of the stories are related but features the same set of characters in different scenarios, Nicolas' character exists as a representation of how one person can suffer and survive through trauma. the whole idea of Nicolas' character stems from a psychological stand point basically.