Alright explanation time.
Have you ever been sleeping and feel like someone is watching you? That's the hidden. They are only visible when you close your eyes and Their looks range to your fears.
They are attached to you basically, watching your every move, and becomes visible when you blink, or when you sleep.
They are only visible to you and you only. Go ahead and close you eyes, right now. It's near you probably, and watching you, they're visible of course, but none of your friends will be able to see it.
They are still there whenever you have your eyes open, but not visible of course watching you, following you.
I know your thinking, my worst fear is of the dark. Well that simply means that your monster/creature/thing, is made of darkness.
There are times when you can view them, but very slightly, and if you're like me, you can learn to communicate to them, and even see them in the flesh. It's hard to do, but possible.
Why am I telling you this?
Well, so you know that you're not alone of course