In an interview with MTV, the actor hinted that Rory may clash with The Doctor (Matt Smith) this series because the Time Lord consistently puts Amy in harm's way.
"Amy's relationship with The Doctor has obviously grown, but Rory's relationship with [him] is really interesting as well," Darvill said. "If Amy wasn't there, they would be really good friends. I think they are really good friends, but as long as The Doctor keeps putting [Amy] in danger, I think Rory's going to get more and more angry about it."
The star continued: "He really just wants everyone to be safe, but in a kind of selfless way. He's not too concerned about himself. Immediately, he's going to panic that he's going to die [if danger strikes], but he's far more concerned about Amy getting hurt."
Darvill went to assert that this season, viewers will see how encountering The Doctor has changed the way that the young married couple view the universe.
"I think travelling with The Doctor on the Tardis [has changed] their lives," he added. "As much as Rory wanted to have a quiet life before [meeting The Doctor], they [now] kind of wait for the next adventure."
Rory marks the first male companion to travel with The Doctor on a full-time basis since Vislor Turlough (Mark Strickson) boarded the Tardis with Peter Davison's Fifth Doctor in the 1980s.
Following the death of Elisabeth Sladen on Tuesday, Darvill's co-star Smith, David Tennant, and Tom Baker all offered tributes to the late actress, who played The Doctor's faithful companion Sarah Jane Smith.
The sixth series of Doctor Who returns with premiere episode 'The Impossible Astronaut' this Saturday on BBC One in the UK and BBC America in the US.
> View a selection of pictures from 'The Impossible Astronaut'
Watch the stars of Doctor Who discuss the new series below: