As a process, regeneration has gotten a little more complicated since its original inception. As conceived and consistently applied in Classic Who, regeneration was comparatively simple. If you suffered a fatal injury you could change into a new incarnation to heal from that injury. The change was how you healed. Of course even in Classic we learnt a little more, like how Romana regenerated for aesthetic reasons, or how regenerating over the limit would disintegrate you as with Azmael, but it was consistent, it made sense and it was a useful narrative device.
And then New Who happened, with the Meta Crisis, with the āhealing phaseā and later down the line with the incredibly poorly defined and self-contradictory ābigenerationā concept.
With the Meta Crisis, why isnāt this more commonly attempted? With the healing phase, why didnāt they justā¦ only do that and not change faces, and how does any of the dialogue about bigeneration make any real sense.
This model attempts to smooth all that over, as much as is possible, as well as drawing a few more esoteric regenerative concepts in from EU like Timewyrm Revelation to create a definitive guide on ājust how regeneration worksā in the current Doctor Who ethos.
A Step By Step Guide to the Process
Step 1: Building the Successor
The process of regeneration actually begins long before the regeneration itself, or even an injury or choice to initiate it. In fact it begins at the moment ones previous incarnation comes into being, be that birth, looming, acquiring a regenerative cycle or a previous regeneration.
In that instant, already, the mind will begin to subconsciously build a successor.
Successors are normally random, influenced by the experiences of their predecessor, built from their triumphs or mistakes or lessons learnt. In Timewyrm Revelation for instance we see a partially formed Eight being built in Sevenās mind during his life, and incarnations being built over life explains why the same Four pops out of both the Dust and Metebelis III regenerations, but a different Six pops out of the regeneration in People Made of Smoke compared to in Caves of Androzani. The faces were shaped by their previous experiences, by the time of Dust, Fourās persona had been mostly solidified whereas Sixās was still greatly variable during People Made of Smoke. One can imagine similar causes for the multiple alternative regenerations out there, Shalka, Unbound, Full Fathom Five, Spiral Scratch vs Brink of Death. The successor is shaped by the life of the predecessor, so the result can vary, but will also follow general trends.
Of course, some Time Lords exhibit far more control over their successors, Romana IIās form was directly chosen by Romana I, the Master exhibits multiple similar looking facial haired incarnations in his first cycle and Borusa picks mostly similar looking bodies in his successive regenerations. River and the Master also both influence their successors even during traumatic regenerations through intense focus. The Sisterhood of Karn naturally possess an elixir that can aid with this process, and even choose a successor for a Time Lord who otherwise is unable or unwilling to consciously do so.
Construction of the successor is a process that continues to some degree right up until the moment of incarnational change into said successor. But thatāll come later. Cause next we have.
Step 2: Regeneration Required
This stepās normally reserved for renegades, itās the moment in which a Time Lord suffers a fatal enough injury for the regeneration process to trigger. This does not guarantee a regeneration, it is merely the moment in which the Time Lordās body begins biologically preparing for a regeneration. It can still be aborted through no negative consequences if needs be. For instance, the Second Doctor was shot through the head in the Indestructible Man, and his body did prepare for regeneration, but the process never fully triggered as he was given the required medical care to survive. A Time Lord can also hold off or halt the process at this point, as shown by Twelve in Twice Upon a Time or the Master in Last of the Time Lords. But this can also have unintended side effects.
Of course death is not the only cause for regeneration, and in fact is a minority cause on Gallifrey itself. The thing about this step is it can also be directly triggered by a Time Lord who chooses, wilfully, to regenerate. Said regenerations are normally far more peaceful and have far less side effects than traumatic regenerations, as they are embraced, not fought, are done in controlled environments and are not pulling double duty preventing a Time Lord from dying outright.
Step 3: Terminal Lucidity
This step doesnāt always happen, and is a result of attempts to delay or hold off the process, or of particularly traumatic injury. This is whatās commonly known as the āhealingā or āresetā step. And the step in which both Ten and Eleven state they can no longer stop the regeneration.
The reason for this is, I propose, the fact that this step occurs only once the regeneration has become a fixed and inevitable outcome. A Time Lord can only heal before regeneration by ensuring the temporal inevitability of the regeneration.
This step can occur at any point right up to at the moment of change itself. Indeed in Touch of the Nuzrah we get an example of a regeneration that is aborted half way through and reversed with no ill effects.
There is no way to heal without ensuring the creation of a successor. Itās not temporally possible, the two events are coupled in time. In fact this can even result in an interstitial or successor incarnation manifesting ahead of time as a āWatcherā. It is even possible for these Watchers to become self-actualised and abort their own creation or supplant their own predecessor, though such things have not been confidently observed.
But what about the Meta Crisis? Weāll get to that one in due course.
Overlapping with the ends of the last step, the moment of regeneration, a flash of light or lightning or colour or build-up of energy begins and the change in incarnation commences. This is the point at which the predecessor changes into the successor. Notably this process can be stretched backwards, as it is implied by Twelve to be influencing the First Doctor during Twice Upon a Time and can also be arbitrarily halted half way through, albeit not indefinitely, as per Devious. This is the moment in which one incarnation becomes the next and the process begins anew.
With a process as temporally complex as this one, there are often after effects, especially in more traumatic regenerations. Amnesia as oneās biodata settles, the new body behaving erratically and the fifteen hour grace period are all consequences of this. Managing after effects is something taught at the academy and some Time Lords, such as Romana, are far more adept at it than others, such as the Doctor.
In addition circumstances also seem to have an impact on the severity of after effects. The Fourteenth Doctor experienced very little side effects, likely due to the unintentional familiarity of the body. Whilst the very traumatic regeneration of the Fifth Doctor left the Sixth Doctor with side effects that persisted for weeks.
Addendum: The Meta-Crisis. Why not always do it?
The way the Meta Crisis works can be extrapolated from the mechanics of the Terminal Lucidity step above. Tenās healing means that the creation of a successor was inevitable, yet none materialised. Except one didā¦ the Meta-Crisis Tenth Doctor.
Rather than changing, the Tenth Doctor exported the āchangeā into growing a half human clone using the biodata input of Donna as a basis. Splitting the incarnational change between Donna and Meta Ten. This bypassed the need to change himself, allowing him to heal with no ill effects, but unintentionally fixed the creation of the DoctorDonna. From that moment on, Donna was always going to touch the hand, to not do so wouldāve created a paradox thatād likely have forced Ten to complete the regeneration.
Thus one canāt merely do the proposed tactic of lopping off a hand and leaving it aside to Meta-Crisis over and over, as without a genuine Meta-Crisis to fix the formation of, the process will simply fail and a normal regeneration will occur instead.
This also, conclusively, means that Post-Journeys End Ten is the same incarnation as Pre-Journeys End Ten. The incarnational change went into the creation of the Meta-Crisis instead.
Addendum 2: Bigeneration, what the hell is going on?
The thing about Bigeneration isā¦ its inconsistent as all hell. Iām just going to list out the relevant quotes
TOYMAKER: If I can interrupt... Behold the game of the Time Lords. A dummy who dies and doubles and dies and doubles. I could play this for 100 years. I'll have vast meadows of Doctors dying over and over again, and I'll never get bored, because...
DOCTOR 14: But you're fine.
DOCTOR 15: I'm fine because you fixed yourself. We're Time Lords. We're doing rehab out of order.
(Doctor 14 opens the doors of the new Tardis and looks down.)
DOCTOR 14: Oh, look! Oh, that's not bad. Wheelchair accessible.
DOCTOR 14: Ooo, jukebox.
(Then he walks out and goes into the original Tardis, and looks round.
Doctor 15 enters his new Tardis and starts fiddling with the controls.)
DOCTOR 15: Okay... Boom.
DOCTOR 14: Oh. You're the old man. You're older than me.
DONNA: Actually, that is true. He's younger because you came after him. So you're the older Doctor.
In the Giggle, whilst the Toymaker speculates he could double the Doctor indefinitely. Fifteen seems pretty confident that heās the product of Fourteenās rehab. Fourteenās whole character arc is that heās running on fumes, imploding, that he chose this form as a warning to stop or else heāll burn himself out. Fifteen isā¦ not perfect, by any stretch, but heās more put together, less burdened by the weight of all that.
DOCTOR: I said the Toymaker... And defeating him took everything. It ripped me in half.
RUBY: But you survived.
DOCTOR: It literally... it tore my soul in half. I can't survive that again.
The Doctor says in the Devilās Chord that bigeneration tore his soul in half and that he cannot survive it again.
DOCTOR: How's your mum? How's your uncle? All good?
In the Legend of Ruby Sunday, Fifteen asks Rose Noble how Fourteen is going. This one has been pointed to as definitive evidence but really it can be read both ways. Though notably Fifteen hasnāt seen the Nobleās since the Giggle and yet knows Fourteen is their āuncleā specifically now.
DOCTOR: I'm okay, Belinda. Okay? Time Lords have their own medicine. Bi-generation. It's left me with a little extra pocket of energy I've been saving just for this.
In Lux the Doctor mentions this, which isā¦ not helpful but is being listed for completeness.
Not quoted because itās in the background but in the Story and the Engine weāre treated to an image of the post-bigeneration Fourteenth Doctor in rehab whilst the Fifteenth Doctor is overloading the Story Engine with his memories.
MRS FLOOD: We've bi-generated.
RANI: Evidently.
MIKE: But... how did you...? Are you both the same person?
RANI: Unfortunately, yes. Our name is the Rani. Although she's become a Rani, while I'm The Rani. The definite article, so to speak. Now, have you got the Vindicator readings?
MRS FLOOD: Here, ma'am. Sorry, ma'am.
When the Rani bigenerates, the successor treats herself as the definitive article and the predecessor automatically defers to that point of view.
RANI: I'm not a child.
MRS FLOOD: Well, you're my child, in a manner of speaking. It could be said that you sprang from my loins.
RANI: That's the most disgusting thing I've ever heard. How's the Doctor?
RANI: The species is barren. We're a biological dead end. There can never be another Gallifreyan child.
DOCTOR: Sometimes I think that's what bi-generation is. A lifeforce trying anything it can to survive.
DOCTOR: Well, it will be our last one if I get this wrong.
DOCTOR 13: Don't get it wrong, then.
DOCTOR: Good idea. This is going to eat my soul. No chance of bi-generation.
In Wish World and the Reality War the bigeneration is treated as a form of reproduction, and Fifteen believes its possible he can do it again, in contrast to the Devilās Chord. Mrs Flood also seems not altogether perturbed by her successor being killed, which is in seeming contrast to her treatment of them in ISC.
This lot is, quite frankly, a mess. But I think I can sort it out. Based on the following facts.
No one In Universe really knows whatās going on. Panjabiās Rani and the Fifteenth Doctor have experienced bigeneration but only from one perspective, in the novelisation Fourteen even admits he has no idea whatāll eventually happen to him, suspecting he may just fade away eventually, although as of the UNIT Website we know that hasnāt yet happened.
Fourteen is treated as āin the pastā by the narrative following it. He isnāt involved in Legend of Ruby Sunday or Empire of Death, he seems to vanish same as Thirteen and backwards do once Sutekh kills all of time and heās not in the Wish World (and neither is Under the Lake/Before the Flood stasis Capaldi).
So hereās my attempt to reconcile propose bigenerationās fundamental mechanics in a way that weaves all these lines together.
The Toymaker makes Bigeneration real, it didnāt exist before this point, it was a Time Lord myth. Similar processes have been observed but not this one. The Toymaker demands the existence of Fifteen by the rules of the Game, but he directly kills Fourteen despite not being allowed to do so, so bigeneration is the compliance.
Fifteen is made manifest as Fourteenās āsuccessorā. He is temporally after Fourteen, including Fourteenās unlived potential future, manifested in whatās normally known as a Battlefield Loop but stabilised by a division of the soul. The Doctor splits in half in order to forcibly manifest his future without destroying his present.
The Doctors beat the Toymaker. Fifteen creates a potential future TARDIS using his prize from the game, obeying the same rules as before.
However, this differs from the usual causal loop now as it was manifested by the rules of play. Fourteen doesnāt have to fulfil the loop, he can choose to, and become Fifteen, if he does so, Fifteenās soul becomes retroactively whole, the rest of his past becomes real rather than projected and he continues on as the definitive Doctor. However Fourteen can also just live with the split soul instead, and either die or regenerate himself. But the permanent division of the soul will be the consequence.
When we move forward to the Devilās Chord, the soul splitting line is ambiguous here, it could either refer to the splitting and then recombination of a true loop fulfilled or the permanent splitting of otherwise. Both events leave scars upon a Time Lordās soul that would prevent the process from happening again in the immediate aftermath.
Fifteen is thus asking Rose Noble partly because his past includes him becoming the Nobleās uncle, but also because he doesnāt know if this Fourteen has done that, he has no way of knowing if heās āthe definite articleā or āone of twoā. We know however from Fourteenās lack of an appearance in the Empire of Death that he is most likely, either way, definitively in Fifteenās relative past. He still exists in the literal temporal present, but in the same way Hartnell does in the Devilās Chord or Twelve does in every episode set between the 1980s and 2110s in stasis.
In the Story and the Engine we get Fifteenās memories of Fourteen, which line up with the Giggle implying that. Up until that point, he was following the same track as the Fifteen of the bigen.
The Rani splits, her successor immediately takes the lead as she believes that, no matter what, her predecessor would not willingly choose to permanently split her soul by averting her existence and thus that she is the definitive incarnation.
Bigeneration as reproduction is first theorised aboutā¦ Fifteen ponders the possibility of a Time Lord bigenerating, choosing to split their soul on purpose, and whether or not their soul could heal to a point in which more bigenerations could occur, this repopulating the species. He isnāt sure if this is possible, just speculating that, ever since the Toymaker made bigeneration real, Time Lord bodies have attempted to perform it on occasion in a last ditch attempt to increase the population of the species.
The Rani dies, Flood leaves. There are two possibilities here for her subsequent actions. Either she chooses to accept the damage to her soul as a result of the bigeneration, or she instead attempts to perform a Silence in the Library and find some way to save herself from being eaten by Omega. Either or is possible.
Fifteen expresses the possibility of bigenerating again, soft implying that Fourteen did definitively choose to become Fifteen in the end and he is whole once more. Although there is room for ambiguity there too.
Quite frankly itās still annoying it has to be this complicated but I think itās the best way of reading the characters whilst also maintaining every single one of the disparate lines about Bigeneration throughout RTD2.
