Re: So, has Moffat brought back the Cartmel Master Plan? (6x13 Spoiler
Maybe The Doctor doesn't even know that it's a lie. Maybe he thinks he is actually the person who he is portraying. He is a timelord and everything he is doing is the truth, the only dishonesty is that he isn't who he claims to be by identity alone. He is still a timelord solving problems, but he's not a Doctor.
But...before Unearthly Child, the
Doctor wasn't a Timelord solving problems. They've very much presented it as him having a few "adventures" before Ian and Barbara that basically involved him watching stuff happen and, when necessary, running away when things got rough. It wasn't until he started traveling with Ian and Barbara, until their joy at traveling the universe started to rub off on him, that he started
enjoying things. That he started interfering, making things better, actually playing a prominent role in events.
He had no reputation whatsoever to give to someone else, all he would have been known for was the Time Lords knowing he stole one of their TARDISes. The only way I could think this as even beginning to make sense would be if he swapped identities so as to not be caught for stealing a TARDIS and then decided to give the TARDIS to this person anyway. In which case, if he was just going to give it to the person he swapped identities with, why did he even steal it in the first place? (Though even this doesn't make sense in the aftermath of "The Doctor's Wife".)
Besides this being a Shyamalan-esque twist-for-the-sake-of-having-a-twist, it would make absolutely no sense from either a plot or a character perspective. It wouldn't even add dirt to the Doctor like you wanted, it would either do nothing at all or it would actually
remove dirt if it turned out the person we've been seeing as the Doctor never stole the TARDIS after all.
