It sounds like you're on top of the situation and have pretty much figured out when the fights are likely to break out and who's the instigator. If you never leave them alone and unattended and continue to be as aware of their body language as you have been, you should be able to nip it in the bud.

Whenever the bully starts growling or they make prolonged eye contact; continue doing what you've been doing such as distracting them or giving your own command version of "knock it off"!


You'll most likely always have to be on guard for telltale signs, but in the meantime you'll be breaking the pattern they've been establishing. With vigilance you should be able to control the situation over time and these events should become rare to non existent.

Good luck!