Here's how Zerxus Ilerez ended up in 'The Legend of Vox Machina' Season 3

Season 3, episode 4 of The Legend of Vox Machina is a major Critical Role crossover event. Not only does the show continue adapting Critical Role's first live-streamed campaign, it also incorporates a key character from Exandria Unlimited: Calamity, a four-part mini-campaign set centuries before The Legend of Vox Machina and run by Brennan Lee Mulligan.

The character in question is the paladin Zerxus Ilerez (voiced by Luis Carazo, who also played Zerxus in Calamity). He is the current owner of the Plate of the Dawnmartyr, one of the Vestiges of Divergence that Vox Machina need in order to defeat the dragon Thordak (voiced by the late Lance Reddick). Their quest brings them to Zerxus' home in the Hells of Despath, where he and cleric Pike Trickfoot (voiced by Ashley Johnson) play a high-stakes card game for the Plate. The sequence tweaks elements from the original campaign, which saw bard Scanlan (voiced by Sam Riegel) gamble for the Plate with a fire giant in the Elemental Plane of Fire.

"From a story perspective, we had an opportunity to combine two story beats from our campaign," Travis Willingham, who voices Grog Strongjaw, told Mashable. (Willingham is also an executive producer on The Legend of Vox Machina and CEO of Critical Role.) The series could take Vox Machina's stint in the Fire Plane, which doesn't have the biggest story hook by this point in the show's timeline, and merge it with the idea that Ank'Harel ruler J'mon Sa Ord (voiced by Mara Junot) would have hidden the Plate in the Hells to keep it as far from Thordak as possible.

"And right after we had finished EXU: Calamity, with Zerxus' fate being sent to the Hells, it just popped up that maybe 800 years later, he's still down there, and that would be a nice thing to weave into the story," Willingham continued. "Particularly some of the lore that was revealed in EXU: Calamity, and how the Calamity kicked off, and why that might be important to larger antagonists in the story that we might try to utilize in a larger way if we get future seasons."

Zerxus' appearance is no brief Easter egg. Instead, he plays a meaty role in the episode, with the show paralleling his complicated relationship to his deity — in Calamity, that's Asmodeus, Lord of the Nine Hells, although he goes unnamed here — with Pike's own doubts in her faith in the Everlight. In their encounter, he also gives Vox Machina a quick rundown of the events of Calamity, accompanied by a stained glass-style animated interlude reminiscent of the campaign's introduction sequence. Appearing in the interlude are Zerxus' companions, the other player characters from Calamity.

"I think there's a hidden desire on our part to incorporate everyone from Calamity at some point," Willingham said. And with more animated Critical Role projects in development with Amazon Studios, including a Mighty Nein series coming next year, a full Calamity adaptation of some kind may not be too far-fetched.

"It's ripe for a movie, a mini-series, something — we're just trying to figure out the best delivery method for it and how it would fit into everything," Willingham said. There's a hidden desire on our part to incorporate everyone from "Calamity" at some point.

For now, though, it looks like we haven't seen the last of Zerxus Ilerez in The Legend of Vox Machina. When Pike and her companions escape with the Plate of the Dawnmartyr, he utters a very foreboding statement: "We are his blood. The time for his ascension draws near."

The words echo those spoken by Delilah Briarwood (voiced by Grey Griffin) and other cultists of the Whispered One — also known as Vecna in the original campaign — all the way back in Season 1. Could this mean that The Legend of Vox Machina is positioning Zerxus as the Whispered One's champion? And if so, would that mean the series is mashing the Whispered One and Asmodeus together? Or did Zerxus choose to serve another deity in the hopes of trying to redeem him, as he hoped to do for Asmodeus in Calamity?

"A Redemption Paladin is still gonna redemption," Marisha Ray, voice of Keyleth, told Mashable. (Ray is also an executive producer on the show, as well as Creative Director of Critical Role.) "I think it's very fitting, because there are several entities in the world of Exandria that could fit that ticket of maybe being redeemed."

"We're hoping we will see some conspiracy theories [about that line]," added Willingham.

On top of prompting fan theories, Zerxus' addition to The Legend of Vox Machina is further proof of why the show is one of the most fascinating works of adaptation on TV today. Zerxus didn't exist as a character when Critical Role's first campaign came out — audiences didn't even get to meet him until months after Season 1 of The Legend of Vox Machina premiered. Yet as Critical Role continues to grow through its various campaigns, it's creating more source material for its animated adaptations to draw from in real time.

"One of my favorite things about working on the animated show is that after the Vox Machina campaign ended, we continued to expand and enrich the world and create history. We created future stories, but we also expanded what the past was," Liam O'Brien, voice of Vax'ildan and executive producer, told Mashable.

"That's really the best thing about adaptations. You can go through and sprinkle in some of the good stuff that wasn't there before," added Ray.

She continued: "I think we're really lucky in the sense that we're developing Mighty Nein in real time with The Legend of Vox Machina, as well as still continuing to shoot Campaign 3 and other ancillary stuff. So we have this 5,000-foot view of everything — except for all the stuff that is to be determined at the end of Campaign 3 — but we can take the Jenga blocks of the story and move them around to fit nicely."

So as The Legend of Vox Machina continues its run, be on the lookout for more substantial links to Critical Role's other campaigns. Zerxus may be the first Calamity crossover, but from the sounds of it, he probably won't be the last.

The Legend of Vox Machina Season 3 premieres Oct. 3 on Prime Video, with three new episodes every Thursday.