WARNING: This article contains spoilers for the Doctor Who Centenary Special, The Power of the Doctor.Jodie Whittaker's final Doctor Who episode failed to give one companion a proper farewell. The feature-length special had a lot to juggle - the Thirteenth Doctor's regeneration, the departures of both Yaz and Dan from the TARDIS, and the returns of classic series companions Tegan and Ace. Unfortunately, this meant that the departure of Dan Lewis (John Bishop) from the TARDIS ended up as being quite abrupt, leaving before the Thirteenth Doctor's final story properly kicked in.
The reasons Dan gives for his farewell certainly make sense - after being shot by a Cyberman, he almost died. Believing that he's pushing his luck too far, Dan decides to return to Earth, saying goodbyes to the Doctor and Yaz before they're both summoned to UNIT. It's an abrupt way to get rid of the Dan, who only returns for the Doctor Who companion support group at the end. It's a disappointing ending for a companion who has been a warm and entertaining addition to the Thirteenth Doctor's TARDIS crew.
Why Doctor Who Sidelines Dan For Whittaker's Farewell
It's entirely possible that, in Chris Chibnall's original plans for Jodie Whittaker's farewell, there was no Dan Lewis. The character was introduced in Doctor Who season 13, otherwise known as the six episode miniseries Flux. There was an original plan for a full 10 episode version of season 13 that was curtailed by the COVID-19 pandemic. It's therefore likely that the dramatic final adventure that convinced Dan to return home to Liverpool was supposed to be the season 13 finale.
With the episode order curtailed, Chris Chibnall is left with a slightly too busy TARDIS for his packed finale. With a plot that spans across Russia in 1916 to a Dalek plot in the Earth's core, with the returns of 1980s companions Tegan and Ace, it's hard to see where Dan would have fit in. The episode is so packed that Bradley Walsh's Graham appears as abruptly as Dan departs. Another possibility is that John Bishop, a hugely successful UK stand-up comic who was on tour during production, was simply unable to commit to extensive filming on the special. This is perhaps why it's Graham, rather than Dan, who Ace meets in the volcano, and why Dan's departure from the TARDIS was hastened.
Dan Needs A Doctor Who Return (With Gatwa's Fifteenth Doctor)
Although Dan's departure is abrupt, it is quite uplifting. His adventures with the Thirteenth Doctor and Yaz has been so inspiring that he's leaving to turn his life around. When audiences met him in season 13, episode 1, "The Halloween Apocalypse", he was unemployed, unlucky in love, and barred from his dream job as a museum tour guide. After traveling with the Doctor, Dan decides he's going to "attack" his life, and make positive changes. He's still struggling to readjust when he's seen at the companion support group, so he should get one last big adventure to properly wrap up his story.
Graham and Dan know where the Doctor's about to drop off Yaz, which surprises her. It's clear that the Doctor reached out to Graham and Dan to pick her up and provide a friendly face. However, maybe it was the Fifteenth Doctor, rather than the Thirteenth Doctor who told Dan where he could find Yaz. John Bishop is a big comedian, so any future return to Doctor Who would be a guaranteed ratings boost. It would also be the perfect way to wrap up Dan's story, providing proper closure on his ambitions for working in the museum and his potential romance with Di, instead of leaving the Jodie Whittaker Doctor Who finale as his last appearance.