What is the Mountain's official role now?
The Mountain dresses like Kings Guard, yet he has no insignia (let alone 7-star insignia) on his breast plate. So, is his official title "Kings Guard who is protecting the king's mother but who does not wear an insignia like all the other Kings Guard"?
Remember Qyburn saved the Mountain from near death after his killing Prince Oberyn. He used steroids (or something) that made him even stronger. After Cersei's "Walk of Atonement", the Mountain picks her up and carried Cersei somewhere. There after, he is always following Cersei everywhere. What is his role?