No clue. He was mentioning my pendent beeing bad and i had to take it off so he'd stop chasing me. And it always says 'you cant run from the law' when trying to leave the conversation.
The being unable to run is normal. It happened to me when having conversations with multiple NPCs. I don't have a technical way to prevent it but I was able to side step it by waiting for him to get close then start a multi NPC conversation with Darian included. Also maybe gift someone the pendent and get a different one.