Spoilers for Westworld Season 3 Episode 6 follow below.

One of the questions that Westworld viewers have been trained to ask ever since the first season aired is, who is secretly a host? Famously (or infamously?) Season 1’s big reveal was that Bernard (Jeffrey Wright) was actually a host, not a human. Season 2 revealed Stubbs (Luke Hemsworth) to be a secret host. And now in Season 3, one of the show’s central protagonists finds himself wrestling with the age-old question: Am I actually a robot?

So is William a host? We’ve actually been asking that question since Season 2. In the aftermath of killing his daughter because he thought she was a host, William (Ed Harris) famously began digging into the skin in his arm, looking for wires or connective markers of some kind. And in the post-credits scene after the Season 2 finale, we watched as William was reunited with his daughter in some dilapidated version of The Forge. She was testing him for “fidelity,” which is what William was testing James Delos for when trying to recreate his consciousness in host form.

So yeah, long story short, we still don’t know if William is a host, but Westworld Season 3 Episode 6, titled “Decoherence,” offered some fascinating evidence to support the conclusion that William is indeed a robot.

At this point in the season, William has been committed to a mental institution. In Episode 6, he’s being prepped for something called “AR Therapy,” and to participate they need to put an implant in his mouth and draw some blood. But as the computer is reading his blood, we see on the screen that it says there is an “unknown protein detected” with a warning labeled “Synthetic Markers Found.” That would appear to suggest there’s something robotic inside William’s blood. The screen flickers, and we see it says, “Tracing Data Transmission. Recipient Server Detected,” with a location of Sonora, Mexico.

Later in the episode, William’s face pops up when Charlotte Hale/Dolores is exporting data from Delos, with the Sonora, Mexico location appearing once again. Charlotte remarks to Dolores that “the tracker in our friend’s blood paid off,” adding, “we’ve got the location you’re looking for.” Is the location where William is, or is the location where William’s data was sent? That much is unclear.

It’s also unclear if all of this evidence supports the theory that William is a host or not. On the one hand, the sedative that the mental institution employees give him doesn’t work, and when Bernard finds William at the end of the episode, he asks him, “Do you know who you are?” Indeed, the entire AR Therapy sequence—in which William confronts different versions of himself—feels like an accelerated version of the maze that Dolores went through in Season 1 to find her inner voice.

On the other hand, it’s possible that when Charlotte pricked William’s neck when she committed him, she was just putting a tracker in his blood to find him. That tracker could be the “synthetic marker” that was found, and William could be otherwise human.

But if this William is a host, then that means we don’t know what happened to William at the end of Season 2. Last we saw, he was going down into the Forge after Dolores and Bernard. Did they whip up a host version of William after their confrontation? Is the real William locked inside the park somewhere? What purpose would that serve?

As with most things Westworld, the more you think about it, the more confusing it gets. But as evidenced by these “clues” in Episode 6, showrunners Jonathan Nolan and Lisa Joy certainly are enjoying toying with this notion of whether William is a host or not. As for when we’ll get a firm answer on that, TBD.

For more on Westworld, check out my full recap of the episode.