What makes Meko and Gizmo so mean?

I have six cats in total, and two of the ones pictured are meaner than a pack of wild dogs when they get riled up. Meko and Gizmo will gang up on the other cats, one in particular, surrounding him and attacking him. When we feed them in the mornings, they form a barrier between the other cats and the food bowls. We have to constantly move all the food around in circles to let the others eat. 

Meko is the smallest one, but the meanest one of them all. A few months ago she climbed in the dryer when I wasn't looking and took a 20 minute spin at full heat. She barely survived, but she's a few sandwiches short of a picnic now. She'll randomly attack the other cats and turn on whomever tries to break it up. Water has no affect on this one. I have to squirt her with lemon juice. 

Photo submitted by: Anon
Date last updated: 09/14/07