I want to start by saying that if this has been mentioned in a thread before then forgive me since I am only online checking the boards in the afternoon.
OK here goes. I think Onaga used the medallion to resurrect everyone in the prison stage to make them part of his army. Hence this is why you see all of the greatest fighters ever there such as Kintaro, Goro, Shau Khan and the others. He did the same with Kitana and now she is fighting for him. I bet this is the issue with Liu Kang, Onaga resurrected him for his army. I would not be surprised that when we see his bio that he is for Onaga now. Hotaru made that choice that all the other warriors will have to make. What do you think??