Warning: SPOILERS for Terminator: Dark Fate.
The big Terminator: Dark Fate twist should feel familiar to X-Men movie fans because it's extremely similar to the reason Wolverine (Hugh Jackman) was sent back in time in X-Men: Days of Future Past. With James Cameron back as a producer and Tim Miller (Deadpool) directing, Terminator: Dark Fate set out to right the franchise as the proper sequel to Terminator 2: Judgment Day. Reuniting Terminator icons Arnold Schwarzenegger and Linda Hamilton, Dark Fate also introduced a new cyborg threat, the Rev-9 (Diego Luna), from a different apocalyptic future ruled by machines controlled by an A.I. called Legion.
In typical Terminator fashion, a lone hero is sent back in time to protect an innocent young woman who plays a vital role in future events: Grace (Mackenzie Davis) is an augmented human sent back to present-day Mexico City to find Dani Ramos (Natalia Reyes) and keep the Rev-9 from terminating her. Luckily, Grace is joined by Sarah Connor (Hamilton), who has spent her whole adult life hunting Terminators in this revised timeline, and they are later joined by Carl (Schwarzenegger), a T-800 Terminator who lives like a normal person and learned the value of human life. But as the heroes fight for the future, fans may feel a strong sense of deja vu because a lot of Terminator: Dark Fate feels very similar to 2014's X-Men: Days of Future Past.
In X-Men: Days of Future Past, Professor X (Patrick Stewart) sends Wolverine's mind, via the time-travel powers of Kitty Pryde (Ellen Page), into the 1970s to find his younger self (James McAvoy). Logan's mission is to reunite Charles Xavier and Magneto (Michael Fassbender) to stop Mystique (Jennifer Lawrence) from causing a chain of events that would lead to mutant extinction in a future ruled by killer robot Sentinels. The twist in Terminator: Dark Fate is that Grace was sent by the future version of Dani Ramos to keep her younger self safe because Dani turns out to be the future leader of the human resistance against Legion. Neither Dani in the past nor Charles Xavier in 1973 were aware of their destinies but both embraced their futures by the end of their respective films.
So, Grace and Wolverine, two reluctant warriors with metal parts inside their human shells, are sent on a time-traveling mission by the leaders of their respective forces to not just defend but motivate their leaders' more innocent and callow younger selves into action. And both Grace and Wolverine are operating under serious limitations: Grace's augmentations allow her to go toe-to-toe against the Rev-9, but after a short period of time, she crashes and needs meds or she'll die. For his part, Wolverine could only remain in the past for as long as Kitty Pryde could maintain their psychic connection. And both Grace and Wolverine reluctantly recruit the help of former enemies, Carl the Terminator and Magneto.
It's not surprising that Terminator: Dark Fate would share X-Men: Days of Future Past's basic concepts because Bryan Singer's fourth X-Men movie (the second in the rebooted X-Men: First Class timeline) freely homaged Terminator's post-apocalyptic, machine-controlled future. The Sentinels in Days of Future Past's dark future are basically Terminators eradicating mutants and, in Terminator: Dark Fate, the new tentacle Terminators also bear a striking resemblance to the Sentinels. In all, Terminator: Dark Fate swiping from X-Men makes the homages full circle.
Ironically, the timelines of both the Terminator and X-Men franchises grew so convoluted that by their similarly-titled most recent chapters, Terminator: Dark Fate and X-Men: Dark Phoenix, which were both released in 2019, the majority of fans rejected both films. Dark Phoenix was a major bomb that ended the Fox X-Men series with an embarrassing failure (although Disney's purchase of Fox meant the X-Men saga would be rebooted anyway). Now, Terminator: Dark Fate also totally failed to recapture Terminator's box office magic, which means the saga that began in 1984 has also been terminated - at least, for now.