I'm not sure why...I'm not a vampire or anything. Altho recently an Imperial soldier was aggressive towards me. It may be because I shouted animal allegiance at a bear attacking another imperial soldier, which then proceeded to kill the soldier, possibly aligning imperial soldiers against me. Well, I went to Stendaar's beacon and the Vigilants attacked me on sight.

Ideas?

EDIT: Now Agmaer attacked me on sight....maybe if I try removing my bounty (I don't have a bounty-but trying it anyway) they will stop?

Either way, probably you have a bounty in the rift. (If so, just pay off your bounty and you should be fine)

But it can be you are infected with "Sanguinare Vampiris". If that's the case, cure yourself at one of the shrines.

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Try using calm spell on him.

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You should consider to download the unofficial patch for Dawnguard. (if you don't have that !!!!!)

i set my bounty in the rift to 0 and he still attacked, also dropped a black soul gem and still the same result. Guards and soldiers in the rift are normal, only vigilants attack me. And no I am not a vampire and yes I have the dawnguard patch active

Have you done any of the daedric artifact quests? If so, you probably have turned them against you. It's no big deal mind you, they're not that hard to avoid/beat!

Also, I've heard that having daedric armour and/or weapons can cause vigilants to turn on you in the same way the ordinators of morrowind would go crazy on you if they saw you wearing even a shred of ordinator armour. I'm not sure on this one, but it doesn't sound completely stupid.