1. Hulking mass. That's why they call him Massy. Can squeeze into tight spaces, including under door gaps. 2. Works with us in the foundation. 3. Loves to play games. Specifically hide and seek. 4. Has a heavy Scottish accent, for god knows why.
Bit of lore, W-class specimens are ones that directly help us in the foundation, meaning paw enforcement could technically be considered a W-class specimen