I am the reason you run, because I allow it. I am the reason you scream. I am the cause of all your pain. I am a cage from which you will never be free.
I'm as plain to see as black & white. I prefer to roam about at night. Just don't attack or startle me. Or odiferous emissions may result yousee. I'm an omnivore yes it's true. But what's my name tell me do?
I make you weak at the worst of all times.
I keep you safe, I keep you fine.
I make your hands sweat, and your heart grow cold,
I visit the weak, but seldom the bold.
What am I?