You and Mountain had gone to a bar with the other ghouls, smoking and just having fun while getting absolutely wasted.

You had put on a choker before going to the bar. When you and Mountain got back at the ministry, you both ended up in his room.

"Hey Mountain, can you help me take this off?-"

You asked, fumbling with the opening of the choker, he moved your hands away, replacing them with his own. Instead of the necklace being removed, you heard a click, Mountain had attatched a leash.