Events of Black Ops
After joining the USMC, he would eventually be recruited by the Studies and Observations Group (SOG). It was here that he became friends with Frank Woods. It was in 1961 that he became part of a mission called Operation Zapata, where he, Woods and Joseph Bowman were to carry out the assassination of Fidel Castro. Upon escaping after thinking they were successful, Mason was captured by Nikita Dragovich and the real Castro and sent to Vorkuta, Russia.
It was here that Mason met with Viktor Reznov, who he became friends with. While Mason was in the labor camp, he was brainwashed by Lev Kravchenko and Friedrich Steiner to become a sleeper agent to assassinate John F. Kennedy. However, Reznov sabotaged this brainwashing to make Mason turn and try to kill Steiner, Kravchenko and Dragovich. While escaping from the camp, Mason returns to the US, but Reznov is killed, which Mason doesn't know.
Mason's brainwashing eventually led him to kill Steiner and Dragovich, but the sleeper agents were awakened. After being interrogated by Jason Hudson and Grigori Weaver, Mason finds out he can translate the numbers broadcast that was initially brainwashed into him. They track down the location of the broadcast, which is where they kill Dragovich and stop the numbers broadcast.
Events of Black Ops II
Between the events of the first and second game, Mason ends up getting married and having a kid, who is David Mason. By 1986, Alex had retired from the CIA, but is eventually drawn back in because of the disappearance of Woods in Angola. Mason and Hudson would eventually find Woods on a barge, battered and bruised and among a bunch of decaying corpses. After being attacked by a Hind chopper, Mason would run into his first encounter with Raul Menendez, where all three would eventually escape.
It was two months later that Mason would go to Afghanistan to try and get some info on Menendez. With the help of Tian Zhao and Mullah Rahman, they fought off the Soviet forces and ended up capturing Kravchenko. As they are interrogating him, the numbers come back to Mason's head and Reznov tells him to kill Kravchenko. Depending on the player's action, they either get some intel or not, but Kravchenko is shot and killed. However, the Muhajideen and Mullah betray Mason and the others, leaving them to die in the desert. It was Mason's mind thinking that Reznov was the one who rescued them, although Woods doesn't think so.
With the intel they got from Kravchenko, they went off to Nicaragua to find Menendez. They enlist the help of Manuel Noriega, who is secretly helping out Menendez, as Noriega frees him after he is captured. Mason and the others end up fighting through Menendez' base and when they arrive at Josefina's, Menendez' daughter, room, Woods becomes enraged and throws a grenade into the room, killing Josefina and presumably, Raul as well.
The last mission for Mason and Woods, taking place in 1989, was a mission called Operation Just Cause, which was to invade Panama. They were planning to capture Noriega and ruin his reputation. Mason tried contacting Hudson throughout, but kept failing to initiate contact. He would eventually reach Hudson and find out where Noriega was hiding.
Upon capturing him, they were told to bring him to a US Army checkpoint. When they reached it, they were in the dark that Menendez set this whole thing up. Mason was captured by Noriega's men upon splitting up with Woods, while Woods would go on to kill the planned target, Menendez. Woods shot the target, who had a bag over his head, and it turned out to be Mason. Depending on where the player shot the target, Mason would either turn up dead or be shown still alive, visiting Woods at The Vault.
