Interesting! I think the dragon does not choose randomly, and the Giants also don't, at first when I started to use regen liberally (after usually not using it) I started to get attacked by Giants in King Behe, and sometimes (very seldom) the Bone Dragon run up to me, hit, and back to his place. Nemesis and Thanatos also target you much more if you happily cast regen a lot. When I cast regen with care, only when I think it is needed, this happens much less or does not happen.
