It’s the question even Mulder (David Duchovny) and Scully (Gillian Anderson) can’t answer: What is their relationship?

In a new promo for the Fox drama, Duchovny and Anderson attempt to make sense of Mulder and Scully’s dynamic: Are they “friendly coworkers”? Partners? “In the second movie we were married, we appeared to be married,” Duchovny says — and despite the fact that 2008’s The X-Files: I Want to Believe never says as much, it’s not the first timeDuchovny has suggested that the pair got hitched somewhere along the way.

Anderson promises that Mulder and Scully are “closer” in the upcoming season than they were in 2016’s event series, and new footage backs up that claim: Mulder tempts Scully with the promise of something “like a date,” and the partners share some suggestive banter about Mulder’s prowess in handcuffs.

“I’d say we’re kind of back to where we were originally, but without the sexual tension,” Anderson says. “Because we’ve already had sex.”

Check out the new promo above. The X-Files returns Jan. 3, 2018, at 8 p.m. ET on Fox.