Luckily this transformation didn’t last for long but it is still an oddity. If nothing else it creates a black spot for time travellers, one period they dare not visit for fear that they will either be transformed or confronted by billions of the worst criminal Gallifrey has ever produced.
It is a strange thought that since only a few people were immune to the transformation many of the established characters who would have existed within the 21st century would also have temporarily into the Master.
Jo Grant, Tegan, Amy Pond, the Brigadier, Elton Pope, Martha Jones all transformed into the Master. Any new character will also have this as part of their backstory, even if they don’t remember it.
How would the Torchwood team have been affected by this? Potentially they might have alien technology that protected them. Even if they different it is interesting to ponder whether Captain Jack, if he was on Earth at the time, would have been affected given that as he hails from the future he might not have been human enough for the transformation to effect him.
We also know that a young River Song, still going by the name Melody, was on Earth during this period. Would her TARDIS influenced genes have made her immune? She might have been human enough to be transformed into the Master, which might have had an unusual effect on her Time Lord gifts.
There could be a lasting effect from the transformation. Although restored to normal every human might still have a lingering piece of Time Lord DNA submerged inside them. This could potentially be reactivated later.
It is also worth noting that Melody Pond gained her abilities just by being conceived in the TARDIS. Could all future generations have elements of Time Lord gifts within them. This might eventually lead to the transformation of the whole race.
In the novels, especially those related to Faction Paradox, it is suggested that the Enemy that engage in a Time War with Gallifrey could be humans from the future. Other sources have also suggested that the Time Lords are humans from the future.
It would be an interesting twist that the Master’s evil act allowed humanity to reach the next stage in their evolution. This would make him an incredibly important person in the web of time. It could be that the Time Lord’s allowed his criminal acts because some secretly knew that he’d be responsible for creating their race.
The consequences might not just be physical. The transformation could leave psychological damage. Couples might never recover due to submerged memories of when they both became the same person.
There could be those who develop a split personality based on the Master’s personality. These lost souls might think they are the real article, trapped in a human body. What lengths would they go to in order to regain their ‘true’ form?
We can also ponder what the Master Race were up to. We saw a relatively small number of them and if they were able to act independently then they could have been carrying out thousands of plans. Plenty of material for adventures.
Covert organisations and those dealing with exotic technology could potentially have been looted by the Master Race. Even if they believed that they wouldn’t be transformed back they still might have moved technology they felt was interesting or useful.
When the members of the organisation changed back they could have no memory of what they did with the missing technology. This could lead to adventures where the organisations try to reclaim the missing technology or the wrong people find it first.
There could potentially be non-human species on Earth at this time. An adventure could be built around an alien invasion which goes very wrong when all the humans become the Master. The adventure could be run from the perspective of the would-be alien invaders or even a whole group of Masters.
We could also imagine that UNIT might have a prison for aliens. With the guards all suddenly changed into the Master they might decide to release the aliens, leading to a number of adventures afterwards with the PCs trying to recapture the aliens.
The Master might also decide that he doesn’t need the competition and decide to execute the alien prisoners. Players could be these aliens, trying to escape with their lives or they could be time travellers who find themselves having to protect alien criminals.
Ultimately I don’t think we got to see what would really happen if everyone became the Master. The very definition of his character is that he is superior to others. If everyone is the Master then no one is. Everyone would be equal.
Rather than Master Race would worked towards a common goal I think we’d see instant chaos as each Master tries to bend others to his will. PCs could take advantage of this, sowing seeds of discontent.
Adventures could be built around the warring Masters, groups forming alliances only to betray each other moments later. A group of Masters who stumble across a TARDIS might decide it is best to leave and come back when the dust has settled. This could lead to a campaign where everyone is the Master.
There is also potential in repeating the situation with another person acting as a template. Any species that thrives on assimilation or increasing their numbers might try to learn the secret of this technique.
The good guys might also have reason to use the technology in dire situations. One could imagine a doomsday scenario in which the survival of the human race depends on everyone becoming Captain Jack or the Doctor.
If all of this is to much to include in a campaign setting you might want to have this be another event swallowed up by the cracks in time. Now no one remembers anything special about this Christmas.
The only consequence of this would be that the ‘death’ of the 10th Doctor would also be erased. Could this lead to an older 10th Doctor meeting the 11th Doctor? Would he still regenerate but under different circumstances?
Could it be that this erasure destabilises the Doctor’s whole timeline? If so then his time could be running out.