Doctor Who: 10 Huge Questions After The Power Of The Doctor
4. How Come Graham Was At The Volcano?
The sudden appearance of Graham O'Brien at the volcano felt somewhat random, and it does indeed take the Doctor by surprise. She asks the very same question, "Graham, how did you get here?" but he’s hardly got the time to answer. When we last saw him, he was bonding with his grandson Ryan, teaching him to ride a bike just as he’d been doing with Grace when she was alive. But they didn’t leave the Doctor just to continue with their ordinary lives.
Months of having to work without her (in Revolution of the Daleks) gave them a taste for protecting the planet while she was away. And with the Doctor’s blessing in the form of psychic paper, that’s exactly what they've been doing.
Other work commitments meant that Tosin Cole was unable to return as Ryan for Jodie Whittaker’s sendoff, but Graham says he’s in Patagonia, presumably investigating another volcano. In short, Graham is there doing his job. It’s a plot contrivance of course, since he just happened to be at the right one, when the volcanoes were active right across the globe.
He gets to meet Ace and fans are already shipping them - hard not to, considering the wonderfully natural chemistry present in their scenes together.