Apocalypse is a recurring theme of Umbrella Academy. There is one in every season in which someone from the titular academy is always behind, and the Hargreaves siblings try to save the world from it.
This time, the new apocalypse does not have a deadline. It happens in a parallel universe where the siblings end up after attempting to return to their original timeline, where they find themselves replaced.
The culprit behind both apocalypses of the first two seasons is Vanya Hargreaves, the most powerful superhero of the Hargreaves siblings. She accidentally caused the disasters that the number 5, the time-travelling Hargreaves, always comes forward to restore.
But this time, the apocalypse is not any chain of events that will annihilate the world; instead, it’s a Kugelblitz, a concentration of power gradually engulfing the whole space-time continuum. The Hargreaves family must stop this monstrosity in their basement before it erases their entire existence.
And this time, the Hargreaves siblings are not alone. This parallel timeline happened due to their interaction with Sir Reginald Hargreaves back in 1963, who adopted them in 1989 in the first place.
Realizing his mistake, Reginald adopts the other seven superpowered children born that same year and creates 'Sparrow Academy' instead of 'Umbrella Academy.'
The new Hargreaves siblings of Sparrow Academy are not as friendly as their counterparts. Instead, they grow an instant dislike for the former Hargreaves superheroes and act hostile toward them.
Over the season, they are seen to have animosity towards the Umbrella Academy over many things and plot to gain the upper hand or exact revenge.
Reginald is seen to be a bad father till the very end. His adoption of superpowered children might look like an act of humanity. Still, in the latter course of action, it is revealed that he has an ulterior motive for this action, albeit his plans are still unclear.
Over the two seasons, he always acts harsh and blames the Hargreaves siblings for not pushing further. In the latest season, he seems to get the taste of his own medicine - Sparrow academy children drugging him to remain docile and subjugated to them.
Still, he manages to turn the events by revealing one of his biggest secrets of saving the world, sacrificing his adopted children while keeping his final plans a secret.
Vanya Hargreaves has a significant change in this season. She gets an epiphany about her life and changes her name to Viktor, paralleling the real events, the character’s actress Ellen Page transforming her gender and renaming himself Elliot Page.
With these events happening and an ambiguous ending of season three, the questions remain, how many more secrets does Reginald have? What is his actual final plan for himself?
The adaption of the comic book written by My Chemical Romance frontman Gerard Way has been streaming since 2019 and the possibility of a fourth season may have the answers to them.