Disclaimer: Not mine, don't sue

PETER
Fools.
They believe that Remus is the spy for the Dark Lord?
Not likely.
Even if he is a Dark Creature.
No, I'm the Spy.
The one they would never suspect.
No, they'd never suspect me.
I'm just Peter, who follows James around like a puppy.
And now they have made me their secret keeper!
My Lord will be very pleased when I inform him of their whereabouts.

VOLDEMORT
Ah, my spy, Peter.
So quick to follow those more powerful than him.
And now he betrays his best friends for me.
I cannot wait until they realize that they were betrayed by their supposed 'best friend'.
I may actually have to reward him for this.