To preface this, I have seen the question multiple personalities characters speech in text and I feel that my question is different enough, to warrant a separate question.
In my book, a character has multiple personalities. In one, personality defining scene, whilst she is playing a game. her normal personality (Niar), is overtaken by the gaming personality (Suoti).
I have thought about changing the name straight away - but I feel that it is really disorienting for the reader.
Right now I have written:
"My name is Eben - who are you?" inquired the old man.
"I'm Suoti," replied Niar, using her pseudonym. Suoti was much better at games than she was.
My problem is now - how do I carry on, in a way that doesn't disorient the reader. At the moment the reader doesn't know that Niar has multiple personalities (she only recently entered the storyline). The book is written in the third person omniscient, so anything goes.
Should I continue using Niar, or Suoti, or another option, in the rest of the scene, and how can I do this whilst not disorienting the reader?
EDIT
Due to some misunderstandings, I would like to say that this is not a case of dissociative identity disorder, rather a byproduct of a magical accident, so any points over the reality of the personalities interaction, whilst helpful and very much appreciated is not applicable to the question.