It's just a feeling, at first
An itch, almost:
What's that lurking over your shoulder?
You know there's nothing there,
So why do you insist on turning
Your head to check?
Sure enough, you see
Nought that doesn't belong;
A false alarm.
But the feeling doesn't go.
You can fight it, delay it all you like
But sooner or later
You'll have to check again.
And this continues anon.
A too-dark shadow,
An uncanny reflection,
A peripheral phantom -
If there was truly nothing there
Then why do you still feel it
Behind you?