Warning: this story contains spoilers for Sunday's "Rogue Element" episode of The Walking Dead. Who is Stephanie Vega? In "Rogue Element," Eugene (Josh McDermitt) gets answers when he investigates Stephanie's mysterious disappearance. After arriving at Commonwealth to meet the woman whose voice came over his radio back in Season 9, call sign "Tater Bug" found love with "Blue Weevil": Stephanie (Chelle Ramos). Suspecting his girlfriend has been kidnapped by a rogue element of conspirators within the Commonwealth government, Eugene and Princess (Paola Lazaro) work together to expose the truth.
Eugene investigates Roman Calhoun (Michael Tourek), a purported plumber he saw leaving Stephanie's apartment building the night of her disappearance. He stakes out Ruby's Plumbing Co., a suspected front and base of operations for co-conspirators of the "head honcho": Male Suspect #3. Presenting evidence of a forged work-transfer request, Eugene suspects someone in the Milton administration falsified the transfer to cover up Stephanie's disappearance.
When Eugene and Princess are arrested for breaking into Calhoun's apartment, Deputy Governor Lance Hornsby (Josh Hamilton) verifies Calhoun is a plumber sent to fix a sink in Stephanie's building the night she went missing. If Eugene agrees to sign a statement declaring himself emotionally distraught and in a paranoid state following the disappearance of his girlfriend, Calhoun won't press charges.
After breaking into Ruby's to find Stephanie with Calhoun and Hornsby, Eugene realizes: "There was never any Stephanie." She's an undercover agent or con artist, her relationship with Eugene a total fiction.
Eugene deduces Hornsby used Stephanie to trick him into revealing intel on Alexandria and its allied communities. The ruse exposed, Hornsby says the gaslighting and lies and manipulations was worth it to get Eugene's people to the Commonwealth. Hornsby then reveals the truth about Stephanie: "Stephanie" is Shira, and she hates Iron Maiden.
Later, a woman with a familiar voice steps out of the shadows. "Eugene, I need to talk to you," she says. "Tater Bug. This is Blue Weevil to Tater Bug. Please come back." It's Max (Margot Bingham), the woman who saw Eugene getting ice cream with "Stephanie" in Episode 5. "It's me... I'm the one you were talking to on the radio."