Run and hide
A bit more like an AI now, and slightly less psychopathic, the above animation shows the red agent shooting one white agent dead, then taking cover when the other becomes visible to it. It's always trying to find somewhere to hide, but only when it doesn't have to run too close to it's target.
Granted, it may currently view the stairs as cover, but that's because the cover finder system is looking at possible paths and ignoring height.
Next up will be some form of patrol route, I think. Pretty much every game since Space Invaders has had it's AI follows set paths around the world so it's probably time to add that in.