Doctor Who's 12th Doctor has gone from surly and disparaging to caring and compassionate in the span of two seasons, but Peter Capaldi's iteration of the famed Time Lord will change once again as season 10 begins.

'Doctor Who' Season 10: 'This Could Be My Final Year', Is Peter Capaldi Ready To Regenerate? [POLL & VIDEO]

Loss has a way of remaking the Doctor, and the end result is never good. Each regeneration has dealt with death in their own way, but based on Twelve's history, viewers can expect the current Doc to take Clara's departure with a hefty dose of despair.

"It's been nice to see him more cheerful, but of course as the whole [of Series 9] develops, more terrible things happen," Capaldi told Digital Spy. "So in fact, I think by the end, he's going, 'Oh man, I was right, I should've remained cynical and closed off and suspicious.'"

'Doctor Who' Season 10: Will There Be Less Episodes? Steven Moffat Reveals All

Capaldi, of course, couldn't say exactly what mood the time traveler will be in during 2016, but he did acknowledge the Time Lord's rough season 9.

"If you've been following this Doctor, you've seen him go through all those different colours and all those different places," Capaldi teased. "So where he goes now - in series 10 - I don't know, but he's been put through the mill."

What brand of Twelve do you think will appear in season 10? Sound off in the comments below.

Doctor Who is expected to return to the BBC and BBC America later this year. Click the video below to see a preview for the series' latest episode.