DISCLAIMER: Sadly, not Remus Lupin, not Severus Snape, nor anything else spawned of the Potterverse belongs to me, it's all J.K Rowling's.
LUNAR ECLIPSE

I watch day fade with sorrow
It retreats to depths unknown
And I know that I must follow
To face demons of my own

One last glance through the shutters
That shield the final light
My heart, inside me, flutters
The moon is full tonight.

This cursed change will fill me
Fill me with a pain
Twist my nerves and body
'Til few semblances remain

My head is splitting open
A thousand rooms within
The things contained inside them
Chill my changing skin

For the rooms are filled with bloodshed
Blood the moon wants me to seek
The gruesome biddings fill my head
Resist? I am too weak

Each room another bloodied scene
Each one with things to lure,
To tempt the beast inside of me
And make intent impure

For the full moon with it's sickening call
Seeks to free the things inside
To have the horrors of the rooms made real
And no longer can I hide

Sane thoughts are lost in turmoil,
In the mayhem of my mind,
I grip now at the soil
And let loose the things I find

These now unhindered ragings
Cue the last of change's throes
It will bring about the caging
At the heart of all my woes

For now I'm but the poor trapped soul
At the back of this new mind
The dreaded acts I can't control
The moon has me in it's bind

This brute, this creature, monster, beast
This thing I have become
On any blood would gladly feast
Before the rising of the sun

These horrors unrestricted
My terror unrestrained
Of the world before this nightmare eve
No memories remain

Can't fight the reckless bloodlust
That courses through my brain
Can't bring myself this thing to trust
That it will not kill again

Yes, I have felt it while it kills,
And I know that 'It' means 'I'
Yes, I can see the blood it spills
But I'm helpless, I don't lie

For 'til the morning rears it head
This thing has me at it's will
I feel it now, feel what I dread
As the creature makes a kill

In the fast and flurried murder
Fur, flesh, blood and screams
Combine to haunt me further
In the month's impending dreams

But the moon is sinking slowly
Dawn cannot be far now
Rooms close on thoughts unholy
My calmness to allow

Like sand through outspread fingers,
When at last the daylight looms
Vagueness only lingers
Of the thoughts that filled the rooms.

I can feel them slipping from me,
Identity floods in
I cry out in my recovery
And the walls around me spin

Sunlight frees me from moon's orders
And fills horizons all around
And the last of inner tortures
Sends me sprawling to the ground

And my soul remains unbroken
For I've survived all this before
From this terror I have woken
To be myself once more

I cling to walls and memories
To force myself to rise
To see at last the new morn's light
As the sweat upon me dries

But the dawning brings familiar tears
And I weep from shame and fright
The sole foundation of my fears:
On whom did I prey this night?

R. Lupin