WARNING: The following article contains spoilers for the Season 3 premiere of Legion, "Chapter 20," which aired Monday on FX.

Our introduction to the third season of Legion comes through the perspective of a new character, a teenage girl with a potent mutant power that happens to be exactly what David Haller (Dan Stevens) is looking for. By this time, both the audience and David himself are accustomed to thinking of him as nearly omnipotent, but right away we’re faced with the immensity of one thing he can’t do: change his past.

Switch (Lauren Tsai) is first shown in her lonesome daily life in a city as ambiguous as any of Legion’s locations (she speaks in English, Chinese and Japanese, and there are no street signs or landmarks to give anything away). She aces her classes while paying no attention to them, focusing instead on recorded lectures on time travel played on her Walkman. When she begins to seek out David and the cult that’s formed around him, following cryptic public bulletins and solving riddles to get closer, she seems motivated by curiosity almost as much as a need for belonging.

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And who could blame her? Before the Magic Man even shows up onscreen, the time traveler is in too deep to turn back, having triggered a musical number that sends her through a Wonderland-style tunnel into David’s world. “Switch” is a name bestowed on her by one of David’s followers, and she accepts it without protest. She survives a conversation with Lenny (Aubrey Plaza), who is now gleefully serving as David’s gatekeeper.

Throughout all this, and even into her first meeting with David, Switch looks bewildered and uncomfortable, but never incredulous. Her own life, with a world-altering ability that she keeps secret and a distant father who collects robots, is apparently already surreal enough to buffer her for the magnitude of weirdness that one can expect from David. She certainly fits in with the rest of the cast.

Switch’s healthy skepticism might have prevented her from buying into the peace-and-love sales pitch that David gives her, except that their discussion is interrupted by a sudden attack from Division 3. His former friends have found him and know exactly how to take him down, and Switch watches in horror as a katana-wielding Kerry (Amber Midthunder) chops off David’s arm, and his lost love Sydney (Rachel Keller) doesn’t hesitate to shoot him in the heart. David dies -- and then Switch’s power comes into play.

For a show as fond of warping reality as Legion, time travel (beyond the messages that Syd sent from the future in Season 2) might have seemed like an obvious path to take. But despite its chaotic style, the series uses its supernatural elements in moderation and follows strict rules about them. Time travel has a tendency to take over if it’s used in a story at all, as nothing disrupts a plot quite as much as the possibility that the entire thing could be scratched out and replaced by a new timeline. Describing the limitations and consequences of altering the past becomes a necessity that may or may not be of any interest for viewers who have already seen a lot of it in fiction.

Legion wiggles out of that trap by making the consequences unlike any usually associated with time travel: going back too far increases the risk of attracting a monster. To all appearances, it’s a literal one, scary and mysterious enough that Switch’s brief encounter with it is enough to indicate high stakes. What else could (and probably will) go wrong has yet to be seen, but Switch is already pushing her limits to help David.

Does he deserve it? Unlikely. Although he’s committed to his new image as Bohemian wise man, there are plenty of signs he’s still the global threat that turned his friends against him at the end of the last season. His aversion to violence only lasts until he’s in danger, and then he kills readily. His speeches to Switch are not only tinged with madness, but also narcissistic; he still views himself as a god and it pleases him to be seen as a benevolent one, and as a victim. He’s not interested in trusting anyone: “I tried that,” he says nonchalantly. “It’s better to read their minds.”

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On the other hand, his enemies aren’t looking so spotless either, and not just because of how brutal the attack on the cult must have looked from Switch’s point of view. Syd now bears tattoos on her wrists that read “Me First.” Ptonomy (Jeremie Harris) is embarking on an odd second life, with some part of his mind transferred into a robotic body. And there’s the elephant in the room: Amahl Farouk (Navid Negahban), the Shadow King, antagonist of the first two seasons and undeniably evil, is now working freely with Division 3.

It says a lot for Switch that she dismisses Farouk so easily when they meet, calling him a “robot” (which seems to be an emerging theme for the season). David she refers to as a “man,” which is also good news -- unlike Lenny and the rest of the cult, she doesn’t worship him, even after identifying the pregnant virgin among his followers.

That particular twist may be a bigger shock to the audience than to Switch, since we know more about it: the expectant mother is Lenny’s lover from the previous season, whose declaration that she was with child after spending a night with the other woman was probably assumed by most to be drug-addled nonsense. Her continued insistence on it doesn’t prove that Lenny is the father, but it does raise a lot of questions.

Like Switch, we’ll just have to stick around if we want answers.

Airing Mondays at 10 p.m. ET/PT on FX, Legion stars Dan Stevens, Rachel Keller, Jean Smart, Bill Irwin, Amber Midthunder, Jeremie Harris, Aubrey Plaza, Jemaine Clement, Hamish Linklater, Navid Negahban, and Lauren Tsai.