Is there a mod that fixes this?

[Raistlindantilus]

When I cast non-hostile spells like feather or detect life, or protect other, sometimes the NPC target or just an NPC standing close by (if it was a self-cast spell) suddenly thinks I'm going hostile and fights back.

 

Is this a known cause of any mods such as OOO or LAME? I'm not using many mods that would alter the NPC behavior in such a way....as far as I know.

 

Or is it a known bug with a mod to fix?

[Vagrant0]

When I cast non-hostile spells like feather or detect life, or protect other, sometimes the NPC target or just an NPC standing close by (if it was a self-cast spell) suddenly thinks I'm going hostile and fights back.

 

Is this a known cause of any mods such as OOO or LAME? I'm not using many mods that would alter the NPC behavior in such a way....as far as I know.

 

Or is it a known bug with a mod to fix?

It's not NPC behavior, but a setting for each of those effects which is normally something that cannot be changed. The only effect that I remember being unusually hostile was light. Are these spells being cast on NPCs, or on yourself? Do these spells have a scripted spell effect on them? Often, when people make scripted effects, they forget to uncheck the little "hostile" box.

 

But usually, it's best to just let NPCs buff themselves. You wouldn't like having people randomly cast spells at you out of the blue either.

[Raistlindantilus]

Its both self-cast and target-cast spells.

 

For instance I can be standing in the middle of the mages guild next to another NPC, cast feather on myself, and then that NPC thinks I went hostile with him.

 

They usually start by ducking, or shield bashing, or some other move that was added by the Deadly Reflex combat mod. Which makes me think maybe that has something to do with it.

[Khet]

Try disabling DR then testing. If it is Deadly Reflex, replace it with better mods, such as Duke Patrick's stuff (yes, I'm very biased again DR)