Follower Death
The game treats permanent followers in a similar way to essential NPCs, but still allowing the possibility of their death. When your follower would die due to an enemy attack or a trap, they will be incapacitated for some time and begin to recover their health, just like essential NPCs; enemies will stop attacking or targeting them during this time. However, if they lose all their health again during this period, they will die for good. Thus, you should try to move the fight away from them, so that they are not hit by a stray arrow or area-effect spell. They can also die from enemy power-attacks, or from a damage-over-time effect that is stronger than their health recovery.