One of the reasons that the highly successful TV series, Doctor Who has lasted over 50 years is an ingenious plot devise: Regeneration. Not only does it allow for the replacement of the actor, but also injects new life into the show, with a new take on the character.
Each subsequent Doctor is the same, but different, keeping the show familiar and comfortable, yet fresh and exciting as it forges ahead on its long time journey. With an altered personality as well as a revamped look, and wardrobe, the Doctor takes on a variety of new challenges while continuing to grow as a character.
The regeneration process is not completely understood, but that is a good thing because it leaves room for imagination. The Trill of Star Trek come to mind wherein the old symbiote inhabits the new body of the host, and they share memories and personality traits. But that is not the case with a Time Lord. There is no symbiosis, only one individual and one body.
Meanwhile, a blogger noted that, on average, the actor portraying The Doctor has gotten younger, like Mork from Ork. With that in mind, it would make sense that a Time Lord can regenerate only 12 times. Unless, of course, he takes over someone else’s body, like when the Master took over the body of Tremas in The Keeper of Traken. That is somewhat reminiscent of the Goa’uld of Stargate, but again, without the symbiote.
So, how does the Doctor get a new body? Is it a form of reincarnation – the eternal birth-death cycle where a soul moves from body to body? Perhaps not. After all, the new Time Lord is still an adult, still in possession of all of his or her memories. Patrick Troughton, the 2nd Doctor said it was like a caterpillar turning into butterfly.
So, why the personality change? Well, after Jon Pertwee, the 3rd Doctor, turned into Tom Baker, the 4th Doctor, in Planet of the Spiders, it was explained that the Doctor’s brain cells had been shaken up in the process. Since the Doctor is also becoming zanier, that is easy to believe.
But still, there are many unanswered questions: What about the 10th Doctor’s Meta-Crisis? (Journey’s End) You know, the Doctor Donna and the half human Time Lord who went off with Rose to the parallel universe????
Does the Tardis play a part in the regeneration process?? Why didn’t The Doctor’s Daughter get a new body??
What about the Doctor’s Morbius regenerations? (The Brain of Morbius) And why was Romana able to choose her body after trying on a few?? (Destiny of the Daleks)
While regeneration is a good thing, it can also be quite sad. When the 4th Doctor became the 5th, in Logopolis, it seemed so lonely. Sure, he had 3 companions with him, but he had just met two of them, and we’re not really sure if he even liked the third. The same for the 1st, 5th, and 6th Doctors, whose companions were recent additions.
The 7th Doctor was alone when he regenerated into the 8th in the Paul McGann film; the 2nd Doctor was sent into the vortex, leaving his companions behind; and when David Tennant, the 10th Doctor regenerated in the End of Time, he, too was without company, as he wept, “I don’t want to go.” However, he did have some time before hand to say “goodbye” to all of his sidekicks.
Nevertheless, the 3rd, 9th, and 11th Doctors, were lucky enough to have their beloved companions by their sides.
We now know that the 8th Doctor had help from the Sisters of Karn. He was able to choose to be the War Doctor, who, in turn, had two of his other incarnations nearby when he regenerated into the (9th Doctor). All muddying up the numbering as we knew it.
Some incarnations last longer than others, depending more on the actors, than on the dangers faced by the Doctor.
In this recently discovered long lost episode, for example, the Doctor actually regenerates three times !! From Rowan Atkinson… to Richard E. Grant… to Hugh Grant… to…. Joanna Lumley !!!
So, the Moral of the Story is that, whether we are pleased or not when one actor replaces another, we must remember that, it is the Doctor who lives on !!!