This explains soooo much! Filch is portrayed as one of those characters who everyone hates, and unlike other mean characters (like Snape) we never get to see what made him so weird.

I had always suspected that Mrs. Norris was an animagus O.o good one-shot! ~Virgil~

Author's Response: Thanks! As I read through the series, I was always curious about the bond between Filch and his cat. Her name just led me to believe that there had to be more to the story. I can't wait for JKR to write the encyclopedia already! I will be interested to see what she was thinking about, concerning these two.