There are mystery box shows, and then there’s VisionQuest. The new series is the final part of the TV trilogy that began with WandaVision and continued in Agatha All Along — but even though its predecessors ironed out their fair share of enigmas, VisionQuest finds many more to dredge up. Among them is a Marvel villain we haven’t seen in a literal decade: Ultron (James Spader). The “son” of Tony Stark (Robert Downey Jr.) and Bruce Banner (Mark Ruffalo), created to achieve a form of automated peace, Ultron quickly broke bad when he decided humanity was far beyond saving. It took the combined might of the Avengers and the creation of an even more powerful “synthezoid,” the Vision (Paul Bettany), to put a stop to Ultron’s genocidal plans. Vision seemed to vaporize his progenitor at the end of Age of Ultron, and the past 10 years in Marvel’s Cinematic Universe have been peaceful on the AI front. As we learn in VisionQuest, however, Ultron never really went anywhere. He’s living in Vision’s head — “rent-free,” Ultron gleefully says — as has been since we assumed that he was destroyed. Given that the Vision we’re following in VisionQuest isn’t even the original Vision, but a copy created by S.W.O.R.D. and imbued with the old Vision’s memories after the fact, Ultron’s survival feels all the more improbable. So how has he returned to the MCU? The short answer: a retcon.Spoilers ahead for VisionQuest Episodes 1 and 2.Vision didn’t destroy Ultron. He saved him.Ultron is back — or maybe he never left. | Marvel StudiosVisionQuest shows us just how easily a major Marvel moment can be reinterpreted many years later. When Vision confronted Ultron at the end of Age of Ultron, he seemed to destroy the final automaton carrying Ultron’s code in a blast of yellow light. We never saw Ultron smashed to smithereens or incinerated, but chalked that sequence up to a bit of poetic filmmaking on director Joss Whedon’s part. In truth, however, that might have been Marvel’s way of leaving the door open for an eventual return. After all, the Ultron of the comics never stays down for long. He always finds a way back from the brink; in the MCU, Vision might be the key to true resurrection.As we learn in VisionQuest’s two-episode premiere, the “old” Vision — the one who was eventually murdered in Avengers: Infinity War — absorbed Ultron’s source code before destroying his vessel. Seeing as he was partially created by Ultron, it makes sense that he’d be able to keep Ultron in check. Less obvious is how the new Vision — the one we’re following in VisionQuest — inherited that responsibility. The version of Vision he met was a construct created by the Scarlet Witch (Elizabeth Olsen), and her magic was powerful enough to rebuild every part of Vision, including the code hidden deep in his servers. When Old-Vision transferred all that data to New-Vision, Ultron went with him, apparently, alongside other bots like J.A.R.V.I.S. (James D’Arcy) and F.R.I.D.A.Y. (Orla Brady). It’s one of the more confusing wrinkles in VisionQuest, but it’s a small price to pay for the return of a villain with so much potential. VisionQuest is streaming on Disney+.