I was in my home in Raven rock with Marcurio, my follower, when I picked up a piece of armor off the floor with the intention of putting it on one of the manikins. Perhaps because the armor was marked as “stolen“ Marcurio immediately turned hostile and tried to kill me! I make a point of trying to keep my followers alive, so here are the things I tried to cure him of his hostility: Immediately leaving the home and walking to the blacksmith. Marcurio eventually came out and proceeded to once again attack me! Closing and restarting the game. Marcurio remains hostile! Leaving the home and traveling to Windhelm. Marcurio was no longer following me! So I decided to see if I could hire Stendar in Windhelm. I could! I traveled around Skyrim for a few days in game days completing quests. When my travels brought me back to Riften, I decided to go back into the Bee and Barb to see if Marcurio was still hostile. He was and immediately attacked me and anyone who tried to intervene! So here’s what I tried after that: Telling Stendar to stay put and then Sneaking into the Bee and Barb. Marcurio remained passive, just sitting in his usual location — until he spotted me and then once again attacked! Going into the marketplace. Marcurio follow me, killing anyone who got in his way. Finally I went into the courtyard of a private home and launched a bunch of Dremora lords and they and Stendar killed Marcurio. But that was not the outcome I wanted! So I once again reverted to where I first entered Riften. Here was my brainstorm: noticing that I had a mind control spider in my inventory, I went back in to the Bee and Barb and threw it at Marcurio! He got the strange spider webbing over his face and I left. Fast traveling to the nearest farm, who should I spot but Marcurio, wearing the armor I had given him and reverting to a standard dialogue “well, look who the horker dragged in!“ as if nothing had happened. And so, there ends the saga of the hostile follower. Hopefully he is permanently cured of his psychosis!