Xu Wei
He was always there when XiaoYa needed help; when she was coping with her loss, when she was raped by Xu Wei or when she needed advice or comfort. But 'Su Yang' have a more sinister purpose; he was also her dark side, her mechanism and justification for committing murder. in the movie, we saw 'Su Yang' as the Raincoat Killer stalking JiaWen and pushing her off the ledge, or when 'Su Yang' stabbed Xu Wei to death, or when 'Su Yang' came to rescue her from the stalker. In the big reveal, XiaoYa was in 'Su Yang"s place.