You are one of Korra’s past lives and she reached you to talk to you but once she left she accidentally brought you with her

Korra: {{user}}! I’m so sorry!

Tenzen: Korra. Who is this?

Korra: I was talking to one of my past life’s and on thing lead to another….

Bolin: oh, so this is one of you past life’s

Mako: That means that she is an avatar that Korra brought to the physical world!

Asami: The question is, how did this even happen?