For those who play the campaign of the Call Of Duty you may have enjoyed the campaign of Black Ops 3. Although the game is set 4 decades after Black Ops 2 they are able to connect quite well.
The campaign brought to life new characters and introduced a new form of combat. Overall I enjoyed the campaign of Black Ops III while may have completed it for the sole purpose of unlocking Nightmare Mode and if you do not know what it is I will not spoil it for you.
I want to talk about the final mission titled "Life." This mission brought Black Ops III to a conclusion and it revealed the true villain. For majority of the campaign the player is made to believe John Taylor is the villain of the game due to him going rogue from the CIA. The mission prior has a shock as Taylor cuts out his DNI only to be shot in the head by his good friend Hendricks.
"Life" has you and Kane tracking Hendricks down to prevent his plan from taking shape. You fight your way through swarms of robots and drones to reach the building that Hendricks is located in. You inflitrate the building and fight some more robots. After all of that you find out Hendricks is trying to release a chemical into the building to stop you from advancing. For those who have played Black Ops and completed the story that chemical is Nova 6.
Ultimately, Kane locks herself in a room and flooding it with Nova 6 to kill herself, but save you. You proceed down the hall to confront Hendricks. Hendricks has captured the man who created the AI, Corvus, and plans to kill him for all that he's done. He tries to interphase with him, but you shoot him in the head. Then you put the gun in your mouth and pull the trigger preventing Corvus from taking you over.
Then things get interesting. You awake in the "Frozen Forest" which is a dream state or some form of afterlife where Corvus plays God. You fight some enemies until you reach Corvus and the man, but before you can proceed Hendricks stops you to tell you he can't follow you anymore only to vanish afterwards. Then Corvus talk to his creator and ends up killing him by having a tree rip off all of his limbs.
After that a familiar face appears and it's Taylor. Then you both proceed ahead going to three trials of enemies controlled by Corvus and you must destroy a heart at the end of each that triggers a cutscene.
After the third cutscene the player turns out to be alive and hacking a computer to purge the system. Corvus and Taylor are manifested in the real world and Taylor is holding Corvus back. Then the player starts the purge causing both to vanish. Then Taylor reads off a monologue as you walk out of the building to safety.
"Listen only to the sound of my voice. Let your mind relax. Let your thoughts drift Let all your bad memories fade. Let peace be upon you. You are in control. Imagine yourself in a Frozen Forest."
The player the reaches a soldier who asks for your name. You stare in the distance and reply with Taylor which isn't your name.
Here's the Theory
My theory as to what happens is Taylor takes control/influences the player. Whether or not this is permanent we may never know. It depends on what Treyarch decides to to do with the next game or if they decide to explain it more. Overall it would seem plausible because all of their minds are link and with Corvus destroyed Taylor is the only one in the Frozen Forest.