Basically Bison tried to control Charlie, & he ended up at the bottom of the ocean when Shadoloo realized that Bison's control went south. The Illuminati found his body & through telepathy, Kolin (Gill's Assistant) & Urien explained the situation. Charlie's body was dead, but his mind was preserved thanks to Bison's Psycho Power. Kolin convinced Charlie to work with them & used Charlie's memories as a bargaining chip. Kolin also explained that Bison's control failed (on Charlie, Cammy, & the other Dolls) because he forced his will onto others. According to the Illuminati, a mind can only be controlled if the person agreed to be controlled. They gave Charlie his memories back the minute that he agreed to work with the Illuminati. He agreed because for years, when he joined the military, he agreed to make his life not his own. He swore to protect God's creation, his peace, his justice, and turn his fate over to God. All of that changed after what Shadoloo did to him. After Charlie agreed to work with the Illuminati, he opened his eyes to find himself in a test tube with the body modifications you see in Street Fighter V. The modifications were done by Gill himself. This pretty much confirms that one of the members of the Illuminati will be in the game in some way, most likely Urien (if the Siliconera leak is on the money).