[DanaC]

They often play with the idea that regeneration isn't a guarantee. Took them a little while to decide it was even going to be a regular Timelord thing :p The new series has got more of an idea of what it wants from regenerations. The classic series did it differently pretty much every time. About the only consistent feature was that the new Doctor would experience a period of disorientation, often flitting in and out of different generation's mannerisms.

Here's the Fifth Doctor regenerating. He's just exposed himself to a lethal dose of poison in order get an antidote to save his companion, Peri (who hasn't been with him long at this point):



The ninth Doctor's regeneration shows the more modern approach. They've stuck to the same basic mechanism now throughout the new series. There is still a question mark over whether a regeneration will happen, with the Timelord home planet and civilisation gone. But if it happens it pretty much always happens the same way*, with the eruption of light and power.

Which is a big step up from that Wanderer shit they did with the Fourth Doctor (don't feel like explaining that one ;p)

Similar idea of the Doc sacrificing himself to save his companion. But done very differently.




* yes I know there have only been three Doctors and two regeneerations...but only sort of. There was that whole sidestep, false regeneration that turned into an additional sort of Doctor.

And, I really don't fancy explaining that one.