In the HPatPS Scabbers aka Wormtail bit Draco Malfoy on the train when Crayle, Goble and Malfoy came over to mess with Ron and Harry.

I wonder what was going on in Petter Pettigrew’s mind.

“TAKE THAT MALFOY OFFSPRING! I SHALL HAVE MY REVENGE AND YOU WILL NEVER KNOW IT WAS I!”