If you still have the master chief and arbiter model then you can make the scene of halo 3 where arbiter kills truth and gravemind comes in and both stand with backs to each other. And arbiter says we traded one villain for another. Thats exactly what I will do once i complete arbiter model. And good luck for your predator model.
The download for Master Chief is in the description, you can find the link if you click on ">here<", the download for the Arbiter is on the right side of the page it says "Download" However if you cant download it, Ill send you the files