Monarch: Legacy of Monsters, which has become one of Apple TV+'s biggest hits, introduced a surprising twist for fans in its second season. In the episode "Requiem," it is revealed that the Axis Mundi, which connects the Hollow Earth inhabited by Kong's ancestors to the world, actually allows humans to travel through time. Lee Shaw (Kurt Russell) realizes this when he receives a signal sent from a tunnel he discovered in 1982, back in 1962. Another character aims to use the power of Axis Mundi to radically change history.

"Requiem" also introduces Isabel Simmons (Amber Midthunder). Isabel carries a strong connection to the MonsterVerse lore as the adopted daughter of Walter Simmons (Demian Bechar), the founder of Apex Cybernetics, who first appeared in Godzilla vs. Kong. In the episode "String Theory," Isabel explains to Kentaro (Ren Watabe) that she wants to use Axis Mundi to reverse the "G-Day" event, where Godzilla caused massive destruction in San Francisco. While introducing the concept of time travel to a series about giant monsters battling each other may seem crazy, the Godzilla franchise has played with this concept before.

The role of time travel in a Godzilla film first occurred in Godzilla vs. King Ghidorah. Beings known as Futurians from the year 2204 arrive claiming that Godzilla will cause the end of the world, and they travel back in time with scientists to prevent Godzilla's mutation from nuclear radiation. Isabel Simmons' reasoning for using Axis Mundi energy to prevent G-Day aligns with this same mindset; she genuinely believes the world would be better off without Titans.

King Ghidorah has been central to the franchise, serving as the main antagonist in two of the biggest films in the MonsterVerse (Godzilla: King of the Monsters and Godzilla vs. Kong). While Godzilla earns his iconic title as Alpha Titan by defeating Ghidorah in King of the Monsters, Godzilla vs. Kong reveals that Apex used the energy from Hollow Earth along with Godzilla's skull to power MechaGodzilla. Since its release, Monarch: Legacy of Monsters has marked the rise of Apex, and Isabel's desire to use time travel to kill Godzilla shows she is not so different from her adoptive father.

Throughout "String Theory," Lee Shaw is able to communicate with his younger self and convinces him not to make a mistake that has troubled him in his life. This scene works on multiple levels as young Shaw is portrayed by Wyatt Russell; this means fans see not just the same character talking to each other but a father and son pouring their hearts out in their performances. Kurt Russell mentioned in an interview with Collider that he had been waiting for this moment for a long time and that it completely changed the trajectory of Monarch.

Monarch: Legacy of Monsters has opened up many possibilities by merging the past and present chapters of its story. Now that the two Shaws can potentially communicate, this could lead to tremendous changes in the future and even open the door for new Titans to join the series. While most sci-fi shows and films struggle with the narrative device of time travel, Monarch has truly found a unique approach.