The Fallout show's naive Vault-dweller Lucy strikes me as a tricky character to pull off—too wide-eyed and it's just annoying—but actor Ella Purnell artfully balances her performance on the edge between dopiness and competence. I think she responded very successfully to the description that sold her on the part, which was roughly 'Ned Flanders, but with a violent edge.'

In an Amazon Q&A, Purnell said she was aware of the Fallout games because her friends and brothers played them, and when the show's executive producers described Lucy to her, she was instantly on board. "I'm in. I am 100 percent in. Sign me up," she recalls telling them.

The way Fallout's producers described Lucy to her was as "someone who would star in a toothpaste commercial but could also kill you" and "a Leslie Knope/Ned Flanders-type, but with something kind of dangerous lurking there."

"I felt like, 'Okay, I could do this, I could do this,'" said Purnell. "Sometimes you just know, you kind of feel it in your body. But even so, it was such a surprise that I got the part. I couldn't believe how lucky I got." 

The Ned Flanders in her performance is particularly pronounced—her "okie dokies" are just missing the "-ilys," although they're delivered with slightly more of an "I'm about to do something horrifying" edge than Ned's. Lucy errs on the side of her Vault-grown sense of justice and cheerful goodwill, but her naivety is cut by her aptitude for violence and willingness to apply it. It works well.

The same goes for the other leads, who likewise experience conflict between their naive models of the world and the world itself. Brotherhood of Steel soldier Maximus is in some ways a typical underdog, but breaks the mold with selfish and sadistic behavior that makes you question how committed he really is to the chivalrous life he aspires to.

"Maximus is a person who I think a lot of people hopefully find relatable, I do myself," said actor Aaron Moten. "He's struggling with these ideals in his head. There's a pure force driving him in his desire to help people, but he's caught in-between, in this world of wanting to do the honorable thing, but knowing that to reach some status or glory requires action by any means necessary—especially in a world like the Wasteland where you're often put at odds of kill or be killed."

As the before-and-after duo Cooper Howard and The Ghoul, crowd favorite Walton Goggins delivers the most typical arc of the three, I think, as he evolves from complacent nice guy to disillusioned cutthroat. According to Goggins, The Ghoul is the toughest son of a gun he's played.

"I've played a lot of bad-asses over the course of my career, none as badass as The Ghoul," he said. "He's a pretty intimidating guy, but I had never played someone like Cooper Howard, so I watched a lot of Gary Cooper, a lot of John Wayne, a lot of Gunsmoke and I watched a lot of interviews.

"The video that we have from that time, people that populated the screen were well-spoken and gregarious, but also reserved and a little conservative, not just politically, but just the way in which they expressed themselves, they were regal. And I thought, 'Okay, yeah, that's Cooper. He's part of the greatest generation.'" 

Regarding another kind of character progression, fans have attempted to work out what level Lucy would've reached by the end of the show if she were the player in a Fallout game. Given what they found, she might want to grind sidequests before returning to the main quest in the presumed second season.