Terminator: Dark Fate
I was sent here to stop the robot that was sent here to protect the human who was sent here to protect the human who was sent here to destroy the robot that was sent here to vacuum the floor.
I was sent here to stop the robot that was sent here to protect the human who was sent here to protect the human who was sent here to destroy the robot that was sent here to vacuum the floor.
Cueball is on his way to see the new Terminator movie; Terminator: Dark Fate, when Cueball's future self comes back to stop him, trying to convince him that, as always, he will be disappointed by sequels. (This was, for instance, the main joke in the last part of 566: Matrix Revisited.)
Future Cueball (who we shall call Cueball-2) almost succeeds in convincing present-day Cueball (who we shall call Cueball-1) not to go see the movie in spite of good reviews and the fact that the original star Linda Hamilton is back after several movies without her. Due to the nature of time travel, Terminator: Dark Fate actually negates any movie that came after the first two (The Terminator and Terminator 2: Judgment Day). However, they are interrupted by a second Future Cueball, Cueball-3, who states that in his timeline he hadn't seen it but wished he had, making present-day Cueball exclaim that they should go see it together.
Cueballs 1, 2, and 3 are interrupted again by the appearance of two more Cueballs, presumably Cueball-1 and Cueball-3 who have seen the movie, regretted it as Cueball-2 did, and travel back in time to stop themselves from seeing it. In the next panel another 5 Cueballs appear, however, their reasons for coming back have degraded, with the last one stating that he came back simply because, at the time he came from, the theater sold out of tickets because all the time-traveling Cueballs purchased all of them.
A common trope in science fiction is to Set Right What Once Went Wrong, where characters travel in time in order to stop a particular event from happening so as to prevent an undesirable timeline. The Terminator series film series is famous for this time travel trope. The initial 3 films feature a time-traveling robot sent from the dystopian future to kill a particular human, with the future resistance in turn sending a protector to ensure the human's survival. However, the series has never been consistent on even the broadest rules of how time travel affects the timeline, with each movie exploring different possibilities. This is another point of spoof for the comic, featuring multiple recursive time loops until it becomes a jumbled mess.
The final panel also invokes the "killing Hitler" trope. Adolf Hitler was the leader of Nazi Germany during World War II, and it has been a common plot idea to "go back in time to kill Hitler" such as in 1063: Kill Hitler, by presuming that the world would be better if World War II and The Holocaust had never happened. There are also works that postulate that such a killing would have unintended consequences, making things worse (for example, if Hitler had been replaced by a more competent leader, the Axis power might have won the war). In any case, this Cueball is over 70 years too late to kill Hitler, as Hitler is now dead.[citation needed]
The title text is what is said by the next Cueball-11 (the 10th time-traveler), with each link in the chain relating to the Terminator movies. Except at the end where the initial "dangerous robot" turns out to be a robot sent to vacuum the floor. Robotic vacuums, such as the Roomba, are a recurring theme on xkcd. Given Cueball's inclination to experiment with roombas, and his unusual tech problems, it's also quite possible that a seemingly benign floor cleaning robot could cause the downfall of civilization.
The title text split up:
- A robot was sent to clean the floor.
- A human was sent to destroy the robot (this happens in The Terminator)
- A human was sent to protect the previous human (in The Terminator a human was sent back to protect another human, though the protectee was not a time traveler)
- A robot was sent to protect the previous human (this happens in Terminator 2: Judgment Day)
- Cueball-11 was sent to stop the previous robot
Thus Cueball-11 tries to stop the person that needs to destroy the Roomba by stopping his protector's protector, presumably so that the floor will be cleaned in his timeline. It's strange that Cueball would rather execute a complicated time-travel plot than just clean the floor himself, but we've seen him make extreme versions of mundane activities before (e.g. 1017: Backward in Time, which is not actually related to time travel despite the name).
This was the second time travel comic in less than a week, as the comic two comics before this one, 2220: Imagine Going Back in Time, also had Cueball travel back to visit his past self.