Walter Skinner’s history has been elusive, but your episode reflects something he said in the second season about how he had to shoot a 10-year-old North Vietnamese boy during the war. Now we’re seeing this incident more fully.

Right! I had to be reminded of that. [Laughs] You don’t know that much about Skinner, so that was really exciting. In fact, when I had dinner with Mitch Pileggi, I wanted him to remind me what Skinner’s deal was. Was he married or whatever? And Pileggi said, “Well … I’ve been wearing a wedding ring because I forgot to take it off.” I was like: “I’m pretty sure you’re not married. But if you want to wear your ring, I’m O.K. with that.”

What sort of input did you have on the episode? What did you add to it, stylistically?

One thing was when Haley Joel Osment goes crazy and slaughters the villagers, I wanted to add a baby, add a baby crying. When Mulder is flipping through the photo album, I put some of my family photos in there. My mom just died last year, so it was very fresh, and I wanted to give her something. And when we were shooting Vietnam, I see this period beer that the props department has made called Orville. Orville is my dad’s name, so I was like, “What?” Turns out, they had done it as a surprise for me.

Haley Joel Osment gets to play essentially two characters, both of whom seem softer at first, then turn creepy.

It’s tough to do that quickly, to make him be the scared kid and then creepy, because of the horror of what was happening in Vietnam. My one regret was, we wanted to shoot the scenes in order, to have his longer mane of hair and big beard for the present day, and then cut it off for the Vietnam flashbacks. But because the leaves were coming off the trees in Vancouver, we had to shoot Vietnam first.