You knew this was gonna happen eventually. The Doctor is always followed by things that make time go sproing, and this place is no different.
Therefore, as soon as everyone returns from the Wild West, they will find that, along with the ageing/de-ageing effect, a wild temporal anomaly appears! It's a big ball of severely wibbly-wobbly timey-wimey that shows up at a location to be announced in the very near future.
What does this ball do, you might ask? You... are asking this, right? Well, even if you aren't, I'mma tell you anyway. After a sizeable temporal explosion that knocks out time technology for a solid ten miles (which includes the Initiative's tech, as though they didn't have enough to worry about) (O HAY EDIT, FOLKS IN THE LAB CAN NOTICE THINGS LIKE THE LIGHTS GOING OUT OR THE COMPUTER SYSTEM FLATLINING AS A CASCADING EFFECT FROM THE TEMPORAL STUFF GOING SPROING) this energy stabilises into a physical space roughly the size of a city block. Inside this space is, apart from the Doctor, who WAS the detonation, a variable instability.
IT CAN: Strand your character in time but not space, or even further fuck up your character's age, with exactly the same effects as pertains to memory, canonicity, bla bla quantum that the original effect is having.
If your character is stranded in time, he/she/it/they cannot use his/her/its/their tablet unless he/she/it/they ends up in a time in which the Network is still a thing that exists. But what if someone DOES end up in a time with no Network? WUT DO? If one can't lash together an intertemporal communication device out of the local coconuts, have no fear. The Doctor can telepathically pick up on a stranded Transport's cries for help and relay those through the TARDIS' communications system to the Network of the present day.
Aaaand that's essentially ALL he can do.
YES, LADIES AND GENTS, IT'S THE DREADED 'RESCUE THE DOCTOR' PLOTLINE, BACK TO HAUNT US ALL.
I'm going to need a few volunteers for this one, however. I need folks who can:
--Build temporal stabilisers, which can be constructed out of things readily available in Exsilium (No questing for components!),
--Recognise Zero Matter for what it is and process it, again, something that can be done with equipment available in Exsilium,
--Telepathically contact the Doctor for instructions, recipes for zero matter molotov cocktails, the location of the TARDIS' bathroom, whatever one might need,
--Provide moral support,
--Question why we have to save this alien loser,
Anything, really. I don't want to leave anyone out.
As an added note, some folks may be able to communicate with the TARDIS itself. It doesn't use words, more like visual cues and concepts, but it can communicate.
So what's Zero Matter, you ask? Again, I... assume you're asking this. Zero Matter is something that was only mentioned in the Doctor Who Audio story Zagreus and was a bit of a deus ex machina there. It's the same here--a material whose radiation has a quelling effect on nonorganic energies, especially conflicting ones like that of a time/antitime reaction. Oh, well, that's all fine and dandy, but what's that mean for everyone else? WELL. Zero Matter can also, through the power of headcanon and mun fiat, act in a manner very similar to Element Zero from Mass Effect, and interact with the psionic energies of sapient beings bla bla bullshit, giving them psionic powers. This may be a temporary or permanent effect, depending on mun choice.
And you guys are gonna need it because, like a particularly timey-wimey endboss, Zagreus will have to be defeated the best way we all know how: BY BEING BEATEN INTO THE PAVEMENT. HAAAARG.
And once he's well and truly bashed to a pulp, the anomaly will resolve, people will return to the present, some of the ageing/de-ageing will be fixed, and the Doctor will be back. HOORAY! I love how elastic spacetime is, don't you?
And I think that's that. Questions? Comments? Bits I forgot?
ETA: The anomaly will be there for a while, I'm thinking, so we can actually stagger the ageing/de-ageing a bit.