(Warning: Spoilers ahead for Season 1 of HBO’s “Westworld”)

Ed Harris’ “Westworld” character, the Man in Black, was at the center of several of the HBO sci-fi series’ biggest surprises, but the actor himself was initially in the dark about the twists, he tells TheWrap.

The show revealed during its December finale that William (Jimmi Simpson) is the younger version of Harris’ diabolical character, with William’s scenes appearing as flashbacks. As it turns out, Harris was startled when he was casually informed of this on set.

“One of the big surprises was, I saw Jimmi [Simpson] walking by one day — somebody said, ‘That’s you, [but] younger,'” Harris says. “And I went, ‘Oh!’ That was news to me. That was a big one! Then I found out some things about my past that were interesting — and I found out later on that [my company] literally owned this place. I was like, ‘Oh, OK, thanks — thanks for telling me.'”

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Harris points out that perhaps the toughest aspect of filming the show was the fact that its shoot was put on hold partway through Season 1.

“We were supposed to shoot through the season, and we only got through seven episodes, and then we had to shut down for a bunch of months,” the actor says. “Just in terms of that, just in terms of the continuity of it and focus, we were kind of split up. We shot the pilot two years prior to when we finished the first season.”

Check out the interview above.

“Westworld” returns with Season 2 in 2018 on HBO.