'Agatha All Along' cast on the new Marvel series' magic and mystery

Fans weren't the only ones hoping for more of Kathryn Hahn as Agatha Harkness when "WandaVision" ended more than three years ago.

"I was always interested in more Agatha," Jac Schaeffer, who created that series as well as the new Agatha-centric spinoff, "Agatha All Along," told "Good Morning America."

Schaeffer said viewers' overwhelming response to Hahn's performance as the witchy breakout character -- and that viral song -- was a whirlwind ride, but a series focused on her "didn't seem within the realm of possibility."

The showrunner said a year or so after "WandaVision" ended, she was "exploring different characters and different worlds" for other Marvel projects, but she couldn't get Agatha out of her head.

"It just kept going back to her," she recalled. "But it can all just be traced back to casting Kathryn. The joy and complexity and the continued interest in this character is because of her."

Continue reading for more from our chat with the cast of "Agatha All Along."

Agatha makes her return -- but is she evil?

Hahn called it "an actor's dream" to be able to show the range of emotions she was able to showcase on "Agatha All Along," embracing all aspects of her character -- from the dramatic to the kooky.

"I've been blessed enough in this career to be able to jump into different genres," she said. "I've never been really pigeonholed … so I feel like this is, weirdly, the culmination of that ability."

Schaeffer said, "There are so few actors who can do all of those things" required of Hahn in this role, calling it "so fun" and "so fulfilling" to share a creative partnership regarding the character.

As for whether or not Agatha is a true villain, Hahn and Schaeffer have a few thoughts.

Hahn said, "It feels very binary to call someone just bad" -- even Agatha -- and that "there are many things underneath her behavior" of thinking she doesn't need anybody and inflicting pain on others.

"There is much more to explore there," Schaeffer said, adding that she also wouldn't call Agatha "evil."

"I think that as a young person she was told she was bad … and that kind of thing imprints on a person," she explained. "I think she was told a story about herself that she then made true."

Schaeffer points out that Agatha doesn't want to inflict Thanos-level atrocities but also adds: "But she is self-motivated, and so … good luck to you if you're in her path."

Who is the mysterious Teen?

While "Agatha All Along" has its titular character at the center of the action, she isn't alone -- and she's joined by a mysterious goth character known as Teen.

Joe Locke plays Teen, a character whose true identity is hidden from Agatha as he joins her on a trip down the Witches' Road, described in the series synopsis as "a magical gauntlet of trials that, if survived, rewards a witch with what they're missing."

"I think the mystery of Teen is one of the most exciting parts of the show for me," Locke teased.

The "Heartstopper" actor said he enjoyed playing "different layers" and "different complications of the character" and watching him evolve across the series.

"It's a very full arc," he noted. "So, as an actor, that was a really great thing to be able to play."

Getting to know Agatha's coven

Also joining Agatha and Teen on the Witches' Road is a ragtag coven of witches: Lilia Calderu (Patti LuPone), Jennifer Kale (Sasheer Zamata) and Alice Wu-Gulliver (Ali Ahn) as well as bonus companion Mrs. Hart/Sharon Davis (Debra Jo Rupp), who fans met during "WandaVision").

Zamata says Jennifer starts off as "a prim and proper self-care guru kind of person, and then you see that kind of unravel throughout the show."

"She gets really dirty along with the rest of the characters in the show," Zamata continues, "but I think a lot of her guards and walls that were put in place for good reason at the beginning of the show come down over time."

Ahn chimed in to say, "That's true, probably, of all the witches; everyone's kind of an outsider."

As for her onscreen persona Alice, Ahn said "she wants to be invisible, and I think the process of what happens in the series is a process of revealing."

LuPone found a lot in common with Lilia, saying, "I think I am a Sicilian witch."

The Broadway great even touted her own precognitive abilities similar to her character's, adding, "I know things are going to happen before they happen."

Rupp said Sharon -- no longer Mrs. Hart after the events of "WandaVision" -- is "a little fish out of water" among the witches.

Perhaps the most intriguing of all, however, is Plaza's Rio, who she said has "a long, long history and a very, very intense bond" with Agatha.

The "Parks and Recreation" alum called the lineup of actresses "a very powerful group" for her to join, saying, "When you bring women together, magical things happen."

"Agatha All Along" premieres with two episodes Sept. 18 on Disney+.

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