The co-stars chat and joke playfully on a hotel roof during a summer hotel-roof photo shoot to promote the new season (Saturday, 9 p.m. ET/PT). It will be Capaldi’s second season on the 52-year-old British sci-fi franchise and Coleman’s third and last: She confirmed to BBC Radio 1 Friday that she will be leaving the series later this season.

Clara had eroded the Doctor’s standoffish nature by late last season, and their bonding will continue on the popular series, which last season marked its biggest audience (2.2 million viewers).

“The Doctor is a great defender of mankind but he doesn’t really want to personally know that many of them,” says Capaldi. “Clara humanizes the Doctor. … His affection for Clara is very, very deep, so he listens to what she has to say.”

Coleman, who played the companion to the previous Doctor (Matt Smith), says the transition from Smith to Capaldi was smooth, aside from adjusting to the Doctor’s unique ability to regenerate into a different person and actor.

“It’s not often you have a scene where the lead actor you’re working with changes his face and person mid-scene, so that was quite an unusual day,” she says. “But we had a brilliant working relationship immediately.”

Executive producer Steven Moffat says the two had instant chemistry, which isn’t always the case. Changing actors involves risk, especially when casting a Doctor who isn’t “another quirkily handsome young man with interesting hair.”

Capaldi’s Doctor intrigues Moffat. “While he’s quite forbidding looking, there’s a sense of some emotional turbulence about him. You sort of think he’s on fire and he looks more hurtable, curiously, than David (Tennant) or Matt,” the two previous Doctors.

I have also added HQ Photoshoots from their chat!