Author has written 8 stories for Doctor Who, Primeval, and Psych.
I am a mother of three children, aged 12, 7 and 16 months (Here referred to as Dwight, Flower, and Skwerly). I run a restaurant in an 1860's era hotel in rural Wisconsin, and I dabble in fanfiction. I tend to like crossovers because of the opportunities they provide for illuminating different aspects of a character or setting.
I'm currently writing primarily Doctor Who stories at present, though that could change. Davison is "my" doctor, though he's actually my third favorite, after Baker and Tennant. Matt Smith is growing on me.
Concerning Alex, my Doctor Who OC with that most embarrassing of social diseases (Google Kakrafoon): Mary Sue--maybe. But a lot of the protagonists of YA novels are a bit Sueish. She has become a more interesting person as my children have begun to approach her age, and she's taken on some of their quirks and flaws. Yes, she is fully human, no she doesn't have a fob watch. Oh, and if you come late to the series, she's eleven. I don't always remember to state her age explicitly. And she speaks in American idiom because she's from Kenosha, Wisconsin. Alex is an experiment, (author's experiment, I mean) taking a character who inhabits an original universe and allowing an alternate universe version to interact with the Doctor. Alex and Kate are like Mickey and Ricky, in Doctor Who, more or less. Alex is lucky, Kate's trope subversion is that she has to figure everything out for herself, no owls, Time Lords, or bald guys in wheelchairs to bail her out.
Da Rules (subject to change without notice):
I bend the canon, but try not to break it. (New stories or characters have to fit in plausible holes within the original work's timeline., which is why Alex's tenure occurs between the end of Martha's tenure and the start of Donna's.)
Psychic abilities do not vanish just because it's convenient to the plot. Nor do they become ridiculously powerful just because it's convenient to the plot. (Mostly because then you're stuck with them later.)
TVTropes is my other favorite writing website. I could get lost in there for days.