I think T Ray would be good for a sequel because the writer can go more into the Wade Wilson origins and it leaves more room to play with DPs past in a Dp vs T-Ray perspective of who the real Wade Winston Wilson really it. Plus its so many ways you can go with the plot. Also Dr Killebrew would be a great feature just to play on the weapon X program that was slightly skipped in the first movie, it could bring out DPs teleportation and multiple voices, at the same time it could bring Ajax back in a later film with him being more cybernetic due to the weapon X program, this could also link DP in more with the X-men franchise for later films. Mister Sinister or Tony Masters(Taskmaster) would be great for a later movie, just my opinion. There were factors and key characters that were not in the first film, understandably, due to budget and not knowing fan reaction. But i think a second movie would have a lot of different, and wonderful levels to explore even down to touching on the Hydra Organization and bringing Agent Bob back as a sidekick/fall guy (lol).