Everybody is the same person living in their own realms
It's like a movie, but you act in this movie. The movie is about you seeing and "living" with your endless other selves (The people in your life).
We are actually one person and each one of us lives in their own dimension and "you" live and interact with all these characters. The trick here is that you're deceived into thinking we all live in one dimension, one realm and one "life", but the truth is everyone lives in his own dimension, realm and "life" including you.
So, in simple terms, in another parallel "realm" (if we think it's one realm), you are - for example - your neighbor and everything that happens to him and how you treat him. In return, in the same "realm" (if we think it's one realm), you are the other guy you're now, but the overall truth is that you're all one and each one of you experience his very own dimension/realm.