Nightmare

I'm not entirely sure what this is about...

I am what lives between the twilights
when the darkness meets the dawn
I am what haunts the hellish cities
when your world of light is gone

I am what feeds upon the masses
when they sense me drawing near
I linger on within their shadows
and I hunger for their fear

I am what moves within the stillness
like a cat of prey I creep
I am what dwells within your nightmares
while your loved one's sweetly sleep

I am clothed in deepest midnight
and my presence spreads like fire
to embrace the souls of others
is my only true desire

I am who stands upon the shoreline
with a demon's scarlett eyes
I am the tempest everlasting
and the moon's eternal rise

I am your greatest, deepest terrors
I am the dagger in your heart
some call me devil, others angel
are we all that far apart?