Mirror, Mirror

Here I am, behind you
A surprise!
Watch out, you may not be alone
I'm with you everywhere you go

You may not recognize my face-
But that's O.K!
I can't always look the same, you know

Do you like my mask today?
Or did you like that one from yesterday?
I always look the way you want me to,
So when you look behind you-
Nothing will be there

This is who I am-
Your mere reflection on the wall
Mirror, mirror, tell me-
Who is the blindest of them all?