I have gone to Fort Dawnguard to speak to Isran as part of the A New Order quest and when I got there he was fighting with some vampires. I weighed in and helped kill them but also think I hit Isran and now every time I go near there he tries to kill me. Does anyone have any ideas?
From A New Order
Return to Skyrim - I had to run the whole way.
Wait for 24 hours (I went back to Riften), and try again, they were peaceful this time.
I think you need a high sneak level 50+. Stun them with a paralyze spell to keep them from moving, then run behind the wall closest to him and he'll talk to you while you're hidden!
Just wait around for them to kill the bad guys then just use the invisibility potion. You can then walk up and talk to him.
You may contract vampirism from killing vampires. If you have vampirism for too long, this can cause people to attack you on sight wether you have a bounty not.
You should be able to see if you have contracted Vampirism in the menus.
I encountered this problem too. I came to Dawnguard and found Isran and his company fighting vampires. I shot at them with my arrow, but I misfired on one shot and it hit one of Isran's company. Because of this, they attacked me and would not stop. I went back to Riften and found I had a bounty on my head because of it. I believe this is the cause of them attacking you, but for good measure I also waited 24 hours, as suggested above, came back and then I could talk to them.
just cast the illusion spell harmony, or any spell that calms people. it'll basically reset their reactions to you, unless of course its naturally aggressive npc