Scene 1: I'm walking past next door and there's the little dude looking all skittish. When he see me, rather than greeting me as usual he dashes back into the house. I watch him go in but suddenly I hear a hiss and the other cat they have pounces from behind the door and jumps on his head!

Scene 2: He's chilling on our window sill so I go to stroke him. Then that bastard other cat appears! So instead of accepting his strokes, my buddy hisses loudly at me and then bites my hand!

How can I communicate to a cat that I'm on his side against the other little shit? I tried to chase the other one away after the window sill incident but he was so cocky that he ignored me!

Seriously you guys.