Never leave me alone

I am shrill / but no avail
You follow me still
The screen reveals my frown
Fills it wil glee
Night never fails
To locate me

You appear
The only thing that is true
Appearing as a flash
Cutting right through

I realise
Its pleasing after all
You are the constant
I can recall
Complete my world
Fill me with delight
To have you about
Without a doubt