Did you know that you actually can never forget a face? Every single face you've ever seen during your life gets stored into your memories, and gets used up later. For example, in dreams your brain can't just make up a face. Every single face you've seen in your dream, you've seen somewhere once in your life.
And those strange nightmares you've had of those terrible demon-like creatures?
You've seen them around too, you just can't remember. You don't want to remember.