I enchanted up some fire resistance armor for Vorstag, and made him 100% immune to fire. Now, when he rushes into the room to fight the enemy of the moment, I can throw in fireballs without fear of toasting my companion.
Even though he is completely unhurt by my spell, he constantly complains, keeps telling me to watch what I am doing, and reminding me that we're on the same team.
And I thought Lydia got on my nerves.