Executive producers Seth Rogen and Evan Goldberg needed a loud-mouthed, self-involved pain in the costume-covered rear when wrangling the perfect Rex. They found it with Jason Mantzoukas getting on board. Like so many other roles Mantzoukas is famous for, Rex is likable because of how disliked he is by those around him. Arriving as a smart-mouthed, egotistical hotshot, he brought the laughs until his recent life-changing encounter with the Lizard League in Season 2, Episode 5, “This Must Come as a Shock.” Now, with a bruised ego and a dice with death, he’s been pushed into the unthinkable territory of becoming what all heroes should be — just a nice guy.
His heart-to-heart with Eve (Gillian Jacobs) displays a level of decency we’ve not seen from Rex, which feels like a concerning bit of foreshadowing of righting his wrongs all too late. Instead, Rex has been force-fed a slice of humble pie by the Lizard League, making you want to root for him even more. It’s a truly rewarding arc thanks to Mantzoukas’ performance, bringing a level of humility and self-review that he’s never really done with his characters.
As a result, Rex provides a story even more compelling than Mark dealing with relationship dilemmas or threats from another dimension. As Rex explains in Season 2, Episode 7, “I’m Not Going Anywhere,” he needs this, and by getting a grasp on redemption, he’s setting up others to do the same.