Since Gambit is my favorite character, I can confidently say I know everything about him, from his origins and dark past to every minor detail of his powers and the various ways he can employ them. Any X-fan worth their salt knows that it was Gambit who gathered the Marauders as a last favor he owned to Sinister. These Marauders than went on to cull the life from the Morlock tunnels beneath New York. Even the X-men took heavy casualties‘, all came to pass due to Gambits dealings with Sinister. One of the Marauders turned out to be someone who Gambit was familiar with, Sabertooth. Also, this wasn't the first time Sabertooth had worked for Sinister. Now we have these 3 characters tied together. As Wolverine has long and deep ties with Sabertooth, these characters are linked to our title character. During one of Weapon X programs successful reboots, several prison/testing facilities were in operation. One of them, the Neverland Facility, a death camp where captive mutants were given a choice, if they were fit, to join Weapon X or die. The facility was under the order and supervision of Head Scientist Doctor Robert Windsor. However, Dr. Windsor is not who he seems, he is Mr. Sinister in disguise, and only one other man knows his true identity, and that is Sabertooth. During his command of this facility, he would hand pick the best potential gene pools and take them to his own personal labs. Now an even deeper connection to Sabertooth is established along with strong ties to Weapon X. Additionally, He operated the Neverland facility while Weapon X members such as Sabertooth, Deadpool, Agent Zero, Sauron, Marrow, and others were active... and since this is the Weapon X program that was started by the U.S. is also the basis for the movie, along with its Weapon XI plot and many of the character choices. Another bonus! I have discovered, however, that the prison labs we see aren't Neverland, it's at 3-mile Island for the movie. That obviously isn't a problem, if they can add Blob to Weapon X, they can shuffle 'Dr. Windsor' to the movies main lab setting.
With these strong ties to the source material, Sinister is actually a credible addition to the cast. Now Gambit is linked through the source material. The ties that bind Sinister and Gambit are much deeper than most people know. I mentioned above how Gambit gathered the Marauders for Sinister as a favor that was owed: Gambit's powers manifested at 14. By the time he was about 20-22 his powers had began to grow exponentially and he was slowly losing his control of them. At this time in his history, he could charge objects with kinetic energy simply by looking at them and as he started to lose his control, objects would just explode randomly around him because of the overflow of kinetic energy his body generated. This made him a danger to those around him as well as making it extremely difficult to hide what he is. He searched his connections he'd gathered as a thief to find a scientist who could help mutants. He was sent to Sinister. Sinister bargained that he would remove a piece of Gambits brain, greatly dampening his power, but keeping it within Gambits ability to safely control. In return, Gambit was to perform a series of jobs, leading to his final job of gathering the Marauders. However, unbeknownst to Gambit, Sinister has been a part of his life far longer. It was revealed in "X-Men: The End" miniseries that Gambit was... DUM DUM DUM... Sinister's son. More accurately, Gambit is created from the combined genetic material of Sinister and Scott Summers, then he artificially inseminated the genetic material into a 'breeder' for gestation. When Gambit was born, Sinister gave him to Jean Luc Lebeau, leader of the Thieves Guild so that Gambit would be raised in a fashion Sinister could use in the future. As a note: Chris Claremont wrote the story that revealed this revelation of Gambits true beginnings. This is significant because Claremont is the creator of both Gambit and Sinister, along with many other X-Men and villains. Now I have discovered how Gambit is tied into the story in the movie. He is the only mutant to have escaped a Weapon X prison lab that Wolverine is searching for. Could 'Dr. Windsor' be the head of science at said prison lab? We don't know yet.
It is basically known to all that Cyclops spent his childhood in an orphanage. This orphanage was another property of a disguised Mr. Sinister. Sinister such locations in carious regions of society so as to elevate his chances of getting more powerful mutants to add to his banks. We also know that Sinister has always had a fixation with the Summers bloodline. It has even been revealed that Sinister has been manipulating his family’s gene pool for many generations. Cyclops is the pinnacle of power and his genes, when spliced with others, grew immensely in power. I personally think that they added Cyclops to the cast after deciding to put Sinister in, knowing that if Cyke was tied to Sinister, the fanboy's would accept it. Since Sinister is one of the greatest geneticists in the Marvel Universe, I wonder if 'Dr. Windsor' has a part in the creation of Weapon XI in the movie? Can you see all these ties to him? It's like a web of deception and he's at its center. Before I unveil the final proof of Sinister's presence in this movie, I want you all to know that there is NOTHING anywhere that even mentions Sinister's name in attachment to this film, therefore, all of the things I've told you above involving him in the story is just speculation and possibility. HOWEVER, if you examine every casting list on the internet for this movie, you will get names for everyone and who they are playing, all the way down to the 2 pilots in the heli Wolvie is clinging to in the preview... with one exception. An Australian actor named Christian Clark. Not only can you not find out what role he is cast for, but he is the only member of the cast under a complete gag-order. This means he cannot talk about this movie to anyone except to say, "I can't talk to you about this movie." The most you can find about this mans involvement is this brief interview:
And that's all you can find about him and this movie. Why is he the only one who cannot say a word. This guy actually screwed up by even admitting involvement! And there you have it my friends! While I must concede that this obviously isn't 100% certain, I am confident that my months of referencing, research, and thumbing through old comics has paid off and I would say I'm at least 98% sure that my hypothesis is correct. This is arguably the X-Men's most deadly adversary, and he has the cunning, calculating intellect, and raw power to always stay one step of the X-Men and often operates from the shadows without anyone the wiser. This character could be weaved through the main plots, added to parallel plots ever scheming. To see him on the screen would be second in greatness only to Gambit.
Special thanks to hooked777 and alten2345 for locating some vital threads that allowed me to finally lock this down.
P.S. I have also heard some whispers of an X-23 Easter-egg!