The AI right now is a little simple which makes it both extremely dumb and too smart. It is essentially targeting Gale because he has the lowest AC and saves thus he is the easiest to hit. Put mage armor on him and you might see them switch targets a little bit if someone else is squishier.
Which helps not one bit. There needs to be a taunt skill in the game specifically for tank characters. This is the first RPG I've seen without one.
