I was wandering around the Rift, and was attacked by three trolls. After buffing my follower with Courage I look around to see the three legion soldiers I had passed by a moment ago joining the fight. I figured what the heck, they're helping, buffs for everybody! Next thing I know I'm getting gang-[censored] by a troll and the legion soldiers. I'm surprised nobody's attacked me yet for healing them.

I assume it was because the soldiers were "potential enemies" like giants, who only attack if you get too close (or shoot off a magelight too close to them, FYI). I really love the way they have different enemy responses in Skyrim, with enemies that attack on site and enemies that need to be provoked, but really now! You're in a fight with a monster, a traveller casts a spell at you which invigorates you and makes you feel stronger, and your first reaction is to pepper him with arrows? I might be able to believe that from a bandit, but a soldier? Freaking yikes.

You cast a spell on them. So they attacked. Simple as that.

So nevermind that in past games NPC's didn't give a crap what you cast at them so long as it didn't damage them in any way?

They might of been angry because they don't like Magic. Maybe the spell made them angry or removed their fears of trying to kill you. Who knows?

No, it is not. I have used courage on town NPCs and guards and never been attacked.

I once encountered a lone Imperial soldier (his two comrades had already died) fighting a losing battle against three Forsworn. Determined to save him, I rushed into the battle and used a mass paralysis scroll, which paralyzed everyone including the Imperial soldier. That way, I could summon a Dremora and start bashing the paralyzed Forsworn. It turned out to be the winning edge, and the Imperial soldier survived while the Forsworn was slain.

You'd think the Imperial soldier would be thankful after I saved his life, but no, the first thing he apparently did was to put a 40 gold bounty on my head.
So much for gratitude.

Courage should not be considered an attack. Chances are that one of the soldiers got hit a time or two from your character or a follower in the mix. A broad swing or a misplaced arrow will do it.

The AI in the game can be excessively dumb. I got a 10 gold bounty placed on my head during a fight with a random dragon spawn in Winterhold because a poor defenseless chicken got in the way of my Fus Roh Dah. A city guard actually stopped me right in the middle of the fight and demanded I pay the bounty and hand over any stolen goods in my possession.

Ridiculous!

Those chickens are sacred. You don't mess with Hold Poultry.

...but, Mr. Guard, the dragon. It rages. Surely we can sort this out--amicably--AFTER the slaying of the beast?

Um yeah This is Skyrim. Where you can't run as fast as Sabre Cats, You can't jump 7 feet in the air and if you cast spells on random fighting NPC's they will attack you.
They always attack me if i try to help. Other then using area Restoration spells. If i use any other spell on someone during a fight with whatever it may be. I get attacked.

I'd be pretty angry if people were casting spells on me without permission.

Yet sometimes during battle I obliterate townspeople on accident and get to fines lol. Maybe it's the three hit rule.

Ha. Yeah, the AI is nothing to write home about. Let's not pretend it's more than it is. I wish enemies prioritized fighting dragons above the anonymous adventurer who's battling it.

I thought this was the case, but it seems to be random..no priorities.

Sounds like magical 'roid rage to me

I just love it when i run a away from an attacker towards guards, and they run away screaming like little girls

Oblivion's guards we're actually smart and good for something compared to these Skyrim post-arrow-in-the-knee sissies

OP. Often times if you walk up to Imperial Legionairs wandering the countryside they ignore you as long as you don't get to close with a weapon drawn. If you approach with a weapon drawn they will draw their own weapons and ask you to walk away. If you don't..... well they become hostile. Exception is if you are doing/already did the civil war quests on the side of the Empire.

By joining the fight they were likely to close to you with weapons drawn for too long. Crazy, and bad AI.....

@OP... That reminds me of the time I used Kynes peace on a pack of wolves, because I get tired of fighting them. Well, a mammoth was nearby and the shout aggroed it which in turn aggroed the two giants escorting it. oops.

Dunno. Put yourself in their shoes. You're fighting some trolls, you're a figure of authority. Your life is constantly in danger on those patrols because of the Civil War you are trying to quash. Some wacky mage comes out from behind a hedge and wanders up to you with blazing hands looking straight at you. You don't know him from Adam. Then he starts casting spells on you that make you glow. You have no idea what that crazy cloaked bastard just did to you! Not to mention, people in Skyrim, Imperial or not, typically have a negative view of magic.

Dunno about that. Over by Cicero's cart there is a guard tower. I walked up to it and watched as four guards butchered a gang of four bandits.

That is what you get for helping faithless imperial dogs.....
One time my character was standing next to a stormcloak patrol outside of a town. I was looking away from them, had my back to them. Then one of them started talking, saying something about needing me to leave. Turned and looked at them, and all three of them attacked me. For what is was worth, was playing through the civil war aiding the stormcloaks.
After thinking how much of a bad idea that was on there end, you know to attack the friggan Dragonborn, I got an idea.
My previous save was in that spot, with the soldiers behind me. So I loaded that one, and they all they said this time was about joining the rebellion, so they where trying to recruit my nord [censored].
Not sure if this was a glitch in programming of what, but I get a good laugh out of it now

Yes that happens when bandits attack them, but when something is attacking me they don't usually want to get involved. What am i paying taxes for!? (Well, i assume Skyrim's citizens pay taxes )

Though the guards at the Western Watchtower did kill a Saber Cat that was chasing me, but that may be because that happened after the you-know-what attack.

You mean the stay puffed marshmallow man?

Now there's a mod i'd like to see.

Just wait for it. I got attacked by a Stormcloak soldier for using Healing Hands to save his life once. He was the last man standing in his squad after a particularly nasty sabre cat attack, down to a few meager HP, and evidently quite a bit jumpy...since the moment I cast Healing Hands on him, he attacked. Which then prompted my follower, Erik, to attack him and...well, that was the end of that.

Sheesh. See if I try to be nice and helpful again. Silly NPC AI.