Warning: Spoilers Westworld: Season 1 follow.

The secrets of Season 1 of Westworld were locked down tight; not even the actors knew many of the biggest mysteries until they were unfolding in their scripts as they read them. Showrunners Jonathan Nolan and Lisa Joy told the cast what they needed to know for their performances and led them to certain points without giving anything away. This includes the Man in Black reveal.

Jimmi Simpson played a younger version of Ed Harris’ the Man in Black in flashbacks. We saw William’s beginnings in the theme park and his turn from a relatively innocent young man into something more sinister. While talking with IGN before the Westworld panel at PaleyFest this past weekend, Simpson said he and Harris were in the dark about their shared character: “We didn’t know it was happening until it was happening.”

Once Simpson learned the truth, he started watching Harris in scenes. “At that point, he had nothing to do because he’s Ed Harris,” Simpson joked, “But what I did is, I would go and watch him on set and see if I could grab a couple of things he was doing physically and very subtly. That was the only thing as far as the connection for our performances, besides Lisa and Jonah intricately giving us articulate direction each day knowing what the case and end result was. They were guiding us the entire time to do it just so.”

It’s been established that Ed Harris will return for Season 2 of Westworld, even though he “doesn’t have a clue” yet about what he’ll be doing. He told IGN, “Knowing those guys [Nolan and Joy], who knows? I just want to stay as the Man in Black. I don’t want to get put in a samurai outfit.”

And the younger version of the Man in Black? William could appear in flashbacks or in memories, but Simpson isn’t sure if he’ll return. He said, “Honestly I don’t know. I would be pleased as punch to do that.”

Westworld will return to HBO in 2018.

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