5 Timey Wimey Clues To Where Ruth Fits In Doctor Who Canon

One problem with this newest past incarnation of The Doctor is that though she is implied to exist before the Time War, she does not fit into the original cycle of twelve regenerations. We know from Time of The Doctor that each of those twelve regenerations are accounted for and that the Eleventh Doctor being the twelfth regeneration fully expected to die.

That The Doctor did not die is only due to the fact that The Time Lords gave him a new regeneration cycle. This is actually a vital clue to what is going on. It has been established since at least The Five Doctors that the High Council has the power to bestow a new set of regenerations at their discretion. Time Lords have also on more than one occasion attempted to steal The Doctor's remaining cycle and in Let's Kill Hitler, River Song gave up hers to save him.

This all amounts to The Doctor either acquiring at least one extra regeneration on her own or having been awarded one or multiple regenerations from the Time Lords when she worked for them.

Were it an entire cycle it would also serve to explain a much debated scene in Brain of Morbius in which several unexplained incarnations of The Doctor are shown.