Since we can't really control how they respond, it'd be really nice if they had a near-total damage reduction to AOE. That is unless they are the main target.
I'm tired of my Companion dying because they just 'stood in fire' until dead.
FF14 and WoW both do this because they acknowledge the AI is potato-brained.
Note: I'm considering Companions as a "Game System".
You have to learn the rules of the game. And then you have to play better than anyone else.