Much of The Umbrella Academy's second season revolves around the Hargreeves' attempt to stop the end of the world in 1963 Dallas. But after the siblings avert what they believe starts the apocalypse — the assassination of John F. Kennedy and Vanya's (Ellen Page) wrath — they set off another dangerous threat seething in a boy named Harlan (Justin Paul Kelly).
We first meet Harlan when his mother, Sissy (Marin Ireland), accidentally hits Vanya with her car when the confused time-traveller arrives from the future. Vanya, who suffers from amnesia after the incident, is taken in by Sissy and her perverse husband, Carl (Stephen Bogaert). The couple hires Vanya as a caretaker for Harlan, who's on the autism spectrum, and the two form a close bond. Shortly after Vanya is attacked by The Swedes — a trio of brothers who are hunting down the Hargreeves children on behalf of The Handler — she tells Sissy that she has to leave to protect the family. Harlan runs away after overhearing the conversation, and following an intense search, Vanya sees his toy floating in a lake. She uses her superhuman abilities to lift the water and pulls an unconscious Harlan to safety before giving him mouth-to-mouth resuscitation. Although Vanya revives him, she unknowingly transfers some of her powers to him in the process.
Later in the season, Vanya tries to run away with Sissy and Harlan but is stopped by Carl's policeman brother. An intense exchange causes Vanya to lose control, and she's apprehended by the FBI, who believes she's a Russian spy. They torture her at a government building, but Harlan can feel her pain while he's back at the farm with his parents. He enters an unresponsive state as he channels Vanya's energy, causing Carl to try to take him away. When Sissy threatens to shoot her husband, he forces the gun out of her hand and accidentally fires a bullet toward Harlan, who uses his newfound powers to deflect the shot and kill Carl.
Meanwhile, Vanya's rage triggers a whirlwind of sonic energy that quashes her tormentors and begins to rip the government building to shreds. As her powers wreak havoc, they also form a protective bubble around her, which Ben (Justin H. Min) is able to infiltrate. He stops the destruction by talking to Vanya and sacrificing himself to stabilise the noxious outburst. After Vanya regains consciousness, she realises that Harlan has her powers and has also lost control of them. She and her siblings head to the farm where they save Harlan from The Handler, and Vanya takes back her abilities. However, Harlan maintains some of the telekinetic capabilities and practices them on his toy while he and Sissy drive to New Mexico at the end of the season.
Harlan's final scene could very well be an Easter egg for a potential season three. When the Hargreeves return to the present and see that their father now runs something called the Sparrow Academy — not the Umbrella Academy — a silhouette of a new superpowered squad appears, and one of the members is standing next to a small levitating box. Could it be Harlan? A descendant who developed their powers from Harlan? Someone totally unrelated? Since he's not a character in Gerard Way's source material, it's hard to even guess. But with all of the time travelling and tricky loopholes, anything is possible.