Honestly, fans of the ABC hit Once Upon a Time generally agree on one thing: the show was a chaotic, beautiful mess that somehow made us care about fairy tales again. But when we hit Season 5 and 6, things got weird. Really weird. We weren't just dealing with Snow White and Regina anymore; the writers decided to open the door to the Land of Untold Stories. This brought us the Once Upon a Time Jekyll and Hyde arc, a storyline that felt like it was trying to reinvent the wheel of the show’s entire mythology.
It was a bold move.
The show has always been about the duality of good and evil, but bringing in Robert Louis Stevenson’s classic characters felt like a literalization of a theme the show had already been exploring through Regina and Rumplestiltskin for years.
The Arrival of Sam Witwer as Mr. Hyde
When Sam Witwer stepped onto the screen as Mr. Hyde at the end of Season 5, he brought a menacing, physical energy that the show desperately needed. He wasn't a cartoon villain. He was hulking, well-dressed, and terrifyingly calm. Witwer, known for his incredible work in Smallville and Being Human, actually understood the "monster" archetype better than most. He played Hyde not just as a bad guy, but as a man who felt he had been unfairly cast aside by his "better" half.
The show introduced the pair in the Season 5 finale, "Only You" and "An Untold Story." We found them in a Victorian-steampunk world that looked nothing like the Enchanted Forest or Storybrooke. It was jarring.
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Dr. Jekyll, played by Hank Harris, was the polar opposite. He was twitchy. Nervous. He looked like he was constantly apologizing for existing. The dynamic was set up to be the centerpiece of Season 6, and while the actors did a phenomenal job with the material they were given, the writing started to fray at the edges almost immediately. You could tell the writers were struggling to balance this new "science vs. magic" angle with the existing magical rules of the show.
Breaking the Mirror: The Serum Logic
The core of the Once Upon a Time Jekyll and Hyde story was the serum. In the original 1886 novella, the serum is a chemical gateway. In the show, it became a plot device to facilitate the "Split" trope. Jekyll created a way to physically separate his "evil" side from his "good" side. This was meant to be the solution to Regina's problems with the Evil Queen.
But here’s where it gets complicated.
If you separate the bad from the good, does the bad side have a soul? Does it have its own memories? The show argued that Hyde was the manifestation of everything Jekyll repressed—his anger, his lust, his ambition. However, the twist they threw at us was that Jekyll wasn't actually the "good" one. This was a classic OUAT subversion. Jekyll was a man driven by a desperate, unrequited love for Mary (played by Elizabeth Lail, whom you might recognize from You). When Mary didn't love him back, Jekyll used the serum to become Hyde, thinking a different personality could win her over.
It didn't work. It ended in tragedy.
The Real Villain Wasn't Hyde
The shocking part of this arc was the revelation that Dr. Jekyll was arguably more dangerous than Hyde. While Hyde was honest about his malice, Jekyll was a coward who hid behind his victimhood. In the episode "Strange Case," we saw the flashback where Jekyll, in a fit of rage, pushed Mary out of a window after she admitted she actually had feelings for Hyde, not him.
Hyde didn't kill her. Jekyll did.
This turned the whole "once upon a time jekyll and hyde" dynamic on its head. It served as a massive warning for Regina Mills. She had just used the serum to separate herself from the Evil Queen, thinking she could finally be "pure." But through Jekyll's failure, the show proved that you can't just cut out the parts of yourself you don't like. If you do, you might find out that the part you kept is just as capable of horror as the part you threw away.
Why the Arc Felt Rushed
If you go back and rewatch Season 6, the Jekyll and Hyde resolution happens surprisingly fast. They arrived with such fanfare, but by episode 4, they were both dead.
Why?
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There are a few theories among the fandom and critics. First, the show had too many plates spinning. They were trying to deal with the Evil Queen’s return, Emma’s impending death (the "Vision"), and the Land of Untold Stories all at once. Jekyll and Hyde became secondary characters in their own mythos.
The way they died was also a bit of a letdown for some. Hook ended up being the one to kill Jekyll to save Belle. Because Jekyll died, Hyde died too. It’s a biological link—the "original" and the "copy" share the same life force. It was a convenient way to wrap up the plotline, but it felt like we barely scratched the surface of Sam Witwer’s potential as a long-term antagonist. He was easily one of the most charismatic villains the show had produced in years, and he was gone before the mid-season finale.
The Legacy of the Untold Stories
Even though the Once Upon a Time Jekyll and Hyde presence was short-lived, it shifted the show's DNA. It introduced the idea that not every story is a fairy tale. Some stories are horror stories. Some are "untold" because they don't have happy endings.
The Land of Untold Stories was a clever way for the showrunners, Edward Kitsis and Adam Horowitz, to bring in characters that didn't fit the Disney mold. We got a glimpse of Captain Nemo, the Count of Monte Cristo, and even 20,000 Leagues Under the Sea elements. It expanded the world, but it also made the show feel a bit bloated.
Looking back, the Jekyll/Hyde storyline was a bridge. It bridged the gap between the "Regina is a villain" era and the "Regina is a hero" era. It forced the characters to realize that redemption isn't about killing your inner demons—it's about living with them.
Practical Takeaways for Fans and Writers
If you're looking into this specific arc for a rewatch or for writing inspiration, keep these points in mind regarding the narrative structure:
- The Actor Factor: Watch Sam Witwer's performance closely. He uses subtle physical cues to differentiate Hyde from Jekyll, proving that you don't need heavy makeup to show a transformation.
- Theme Over Plot: The Jekyll/Hyde arc is less about the "science" of the serum and more about the psychological reality of repression. The show uses them as a mirror for Regina's growth.
- The "Same Life" Rule: Remember the internal logic the show established—if you kill the original, the split version dies too. This became a major stake for the rest of the series.
- The Lesson of Mary: The tragedy of Mary is one of the darkest moments in the later seasons. It serves as a reminder that the "nice guy" trope can be a mask for something much darker.
The best way to experience this storyline is to watch the transition from the end of Season 5 into the first four episodes of Season 6. Don't expect a season-long epic battle with Hyde; instead, look for the subtle ways his presence forces the main cast to confront their own shadows. It's a masterclass in using guest stars to trigger character development for the leads, even if the guest stars themselves get the short end of the stick.
To get the full picture, start with the Season 5 finale "An Untold Story" and pay attention to how the atmosphere shifts from magical whimsy to Victorian dread. The set design for Jekyll's laboratory is some of the best work the production team ever did, utilizing a darker, more industrial palette that stands out against the colorful backdrop of Storybrooke. This contrast is the visual heart of the Once Upon a Time Jekyll and Hyde narrative, marking the moment the show truly embraced its darker, more literary roots.