SPOILER WARNING: This article contains major spoilers for "Versus Zoom," tonight's episode of "The Flash."
In "Versus Zoom," Hunter Zolomon finally got what he wanted: Barry's speed. However, before he even made it back to Earth-1, "The Flash" flashed back to Zolomon's childhood and revealed the character's Earth-2 origin.
As it turns out, Hunter Zolomon is one of Earth-2's only serial killers. The episode revealed a traumatic event from his childhood, one that parallels Barry's own origin: Zolomon watched his father murder his mother. However, Zolomon didn't have a surrogate parent like Joe West who was ready and willing to take him in; instead, he grew up in foster care, after all remaining family members refused to take him in.
Zolomon grew up to be a serial killer, murdering 23 people before his capture. Instead of jail, he was sent to a psychiatric hospital, where he underwent shock therapy in order to cure his murderous urges. This is exactly what was happening when Earth-2's particle accelerator went off, and it ultimately gave him his speed.
In addition to Zoom's origin, the episode found Cisco tapping a new ability. Using Reverb's glasses, he was able to manually open the breach between worlds with his powers, which is what allowed Zoom to return to Earth-1.
Thanks to his return to Earth-1, Zoom was able to kidnap Wally and demand Barry's speed in exchange. Stuck between a rock and a hard place, Barry chose to give up his speed in order to save Wally. Zoom took Barry's speed, but something went wrong with the transfer, causing Zoom to lash out against Barry. Caitlin begged him to stop, desperately appealing to any part of him that might have felt something for her. Her plea worked, and Zoom took off, leaving Barry powerless but alive.
During the transfer, Zoom answered a few questions for the team, as well as the audience. As it turns out, the Jay that died was a time remnant of his past self, who he convinced to join him. Additionally, he explained why he masqueraded as Jay Garrick: because he enjoyed "playing" a hero, giving the people hope before ripping it away. However, when Barry asked who the man in the mask was, Zoom dodged the question by saying, "You wouldn't believe me if I told you."