The Jennifer Sy is talking about is the one who gives her name to The Jennifer Incidentthe incident in the original Ben died when he was 17.
How is Jennifer connected to Ben’s death? During their mission to find Jennifer, the brothers arrive at a small town in Maine, where they soon discover that Rosie, the owner of a local diner, is really Jennifer and that everyone in town are actually guards for Reginald Hargreeves’ company who are holding her captive and trapped in a time loop, supposedly to protect her.
The brothers manage to get Jennifer out of there, but are intercepted by Jean and Gene, who crash their truck. At that moment, Ben and Jennifer accidentally touch each other and a kind of connection is created between them. Jennifer is kidnapped, but he is able to connect with her mind and see what she sees, and that gives him the clues to be able to find her.
As this happens, it is revealed that as a child, Jennifer was found inside a huge squid and at that point, she uttered the words The Cleanseand that’s why Jean and Gene are looking for her. They believe that Jennifer is the key to restoring the original timeline.
Meanwhile, the brothers arrive at Reginald’s house to question him and discover that they really have no idea how Ben died, because the Reginald from their timeline erased their minds so they couldn’t stop him. The new Reginald uses a machine to give them back their memories and that’s how they finally know what happened on October 14th, the day Ben died.
That day, their dad prepares them for a mission in Moldova in which they must recover a weapon and keep it in a container. Ben did not want to go, but they convince him and soon they arrive at a kind of factory where Ben discovers that the weapon is a girl named Jennifer and decides to take her out of the container. When their hands touch, their powers intersect with something inside Jennifer, and Reginald shoots them both in the head, killing them both instantly. Reginald says that he had to do this because the two of them would have caused a cataclysmic event that would wipe out humanity.
Back in the present, Reginald’s wife, Abigail, tells them that she is to blame for this, since, years ago, she synthesized the element that created the Marigold and accidentally created a substance known as Durangowhich is the opposite of Marigold and when interacting with this substance, they have the potential to destroy the world and all living beings, and that is why Ben and Jennifer had to die.
Now that Ben and Jennifer have reconnected, the siblings must work together to stop Reginald from killing them again, while also trying to stop the world from falling apart.
Who is Jennifer in The Umbrella Academy?
We don’t know much about the origin of Jennifershe is not really the daughter of And Grossmanwhich suggests that she could have been born in a similar way to the Hargreeves, but she was “infected” by the Durango and not the Marigold, which is what makes it so that if one of them touches her, the two substances react, combine and become extremely dangerous.
She herself says that her whole life was a lie and that no one claimed her after she was found inside the Squid, so she was probably an orphan.
One theory could be that the Jennifer from the squid also came from another reality where The Cleanse had already happened, which is why she mentions it when they find her, and why the Reginald from the alternate reality knows he needs to hide her from his own children.