Doctor Who has hinted that Captain Jack Harkness (John Barrowman) may be starting his transformation into the Face of Boe. This transformation is a long time coming, and season 12 may well mark the beginning of Harkness’ change into his final form.
When the Doctor first meets the Face of Boe, he and Rose are witnessing the end of world. They board a spacecraft to personally witness the Earth’s final moments in the year 5 billion, and in doing so, meet the event’s host: a massive floating head known as the Face of Boe. A wise and (very) old being, he ends up crossing paths with the Doctor one last time before his death, passing on one last bit of wisdom that ultimately offers a thread of hope that the Doctor is not, in fact, the last of the Time Lords. Then, during completely separate occasions, the Doctor takes part in several adventures with Captain Jack Harkness, a former Time Agent who is unintentionally imbued with immortality, courtesy of Rose Tyler/Bad Wolf. Incidentally, before parting ways with the Doctor and Martha at the end of season 3, Harkness reveals to them that his nickname as a boy, growing up in the Boeshane Peninsula, was “the face of Boe.” The two characters turn out to be one and the same.
In Doctor Who’s fifth episode of season 12, “Fugitive of the Judoon,” Harkness makes a surprise return - mostly to warn Graham, Yaz, and Ryan that the Doctor will eventually confront “the lone Cyberman.” However, the reason he can’t stay long is because the ship he’s stolen has an “antitheft attack system” in the form of nanogenes (glowing subatomic robots). First introduced in the season 1 episode “The Empty Child,” nanogenes have the ability to reconfigure a person’s physical form. While their presence doesn’t outright explain why Harkness would eventually lose everything from the neck down, it could explain some other physical differences between his past and future selves.
There has been plenty of speculation surrounding Harkness’ transformation into the Face of Boe (a few popular theories point to the Headless Monks, considering their proclivity for decapitations), but nothing’s been confirmed. And given that Chibnall appears to be making attempts to tie up some loose ends in Doctor Who lore with the Thirteenth Doctor, it’s possible that Harkness’ comment about aggressive nanogenes attacking him isn’t as throwaway as it seems. Maybe they’ll ultimately take a toll on his physical form and transform him into the floating head he was always destined to become.
The connective thread between Harkness and the Face of Boe has always been vague at best, with plenty of holes to write it off as simply undeveloped fan service. So, if Chibnall can whip up a clever explanation, it could end up being a clever nod to previous seasons, as well as a character whose entire timeline in general is a bit messy - even by Doctor Who standards.
More: Doctor Who: How Jack Harkness Becomes The Face Of Boe
