Fable-a-lie

I'm the one in the back, the person you see but don't. But Once you've seen me you cannot forget. 
Is it clear to you yet? You know me, you know me when you look into yourself.
But maybe I am not? I don't know.. Because I don't know myself, I'm just a reflection of nothing and myself.. 
I am a lie nothing more, nothing less. but maybe more? I'd like to think that.. 
But I can't say I am. You want to know me, but already do know me. 

That is what I've been told and made to believe.. Or is it? I cannot say