So I had a glitch in my last Skyrim playthrough during the dark brotherhood. I woke up in the abandoned shack and Astrid was just injured on the ground. Dialogue continued as normal, left the shack.
I left the shack and as I did for some reason Astrid did too. Outside, Lydia was there along with my other followers, and Lydia then proceeded to start beating the ever living shit out of Astrid and the others joined in.
So logically I can only assume for some reason the game triggered Astrid as hostile and Lydia attacked. But now I’m head cannoning that Astrid broke in, got caught in the process of kidnapping Eva. And Lydia chased her all across Skyrim beating the shit out of her the entire way.










