My friend
abigailb was reviewing The Doctor Who mega-story 'Trial of a Timelord' over on her journal and she made me think about a theory that I've held for a while about that story that I've never put down in text before. It's an evil thought. Eeeviiiillll. And yet she didn't back-out and showed no fear. So I told her. And then, I felt that this needed preserving for posterity. And here it is, behind the link:
I can never forgive Trial of a Timelord for being the story that introduced Bonnie Langford.
I've got an evil theory about that that is all too plausible. And terrible. Wanna hear?
The Bonnie Langford introduction story was a future story - it hadn't happened in The Doctor's personal timeline yet. We saw a near-future story where Bonnie's character Melanie was *already* an assistant, retold from the record held in the Matrix.
That account was already 'doctored' by The Valyard and wasn't correct - and we find out shortly after that The Master is already in the matrix and can amend things in there also. Shortly thereafter, The Master sends Melanie 'back' to the trial to help the Doctor, for fear of having an adversary that is a distillation of all The Doctor's suppressed evil.
So, the record is already doctored, The Master has access to do more doctoring and we never, ever see a proper introduction of Bonnie's character becoming an assistant..
Hypothesis?
Melanie never was an assistant - she was a creation of The Master, inserted into the already corrupt record of that story, and her being 'sent back' to assist The Doctor was the first time The Doctor meets her.
Why did he do this? Well, The Master certainly had cause to help The Doctor out here, as he wanted to thwart The Valyard (as literally the lesser of two evils) however, The (old-school) Master was a Machiavellian evil, capable of long-term plots and schemes. Let's assume he's playing the long-game here. Sure, he (regretfully) has to help his old adversary out here, as the alternative is too big an inconvenience to suffer, but since we're making changes, why not use the opportunity to slip a trojan horse in to hinder The Doctor later? Create an 'assistant', amend the record to make her look like she's established, and ensure that the events that are happening mean that that future 'adventure' never play-out as they did by giving The Doctor advanced knowledge via the record. Simple.
There's only one problem with all this: If Melanie was a 'plant', why did we never see her try to 'stick the knife-in' at a later date?
The answer is even more cunning. The Master knows that The Doctor is very good a spotting ringers, remember that he know what Turlough was about, pretty-much from the start and he even saw through the Black Guardian's subterfuge as the White Guardian, while attempting to gain the key to time. No, a ringer plotting against The Doctor would likely be spotted, neutralised and possibly even converted to The Doctor's cause - he is after all tricky like that, damn his pure soul.
However, he is loyal to his assistants. What if the 'spanner in the works' aspect was an innocent part of the ringer's character? No subterfuge to detect.
That particular incarnation of The Doctor is possibly the most irascible since the first. He is often dark and grumpy, not a glad sufferer of fools.
And Melanie is... the perfect low-level irritant, concentration-sapper and general spanner-in-the-works - just as she is. Just as she was designed to be.