A random thing that I came up with when I was bored:
A bit of what was going on in Remus's head when he saw Sirius in the Shrieking Shack...
How dare he! How Dare He! He was my best friend!
But... Pettigrew.
And I thought he was a murderer! The rat!
The guy I pitied forever ruined my life and I didn't know it...
Damn you Pettigrew.