Oh, yes, catharsis is an important element (and probably frequently even more so in the writing than the reading). I've not suffered from depression, but I've been in some pretty dark places in my life and writing them out in some form or other, really does help. *nods*

I'm just far more cautious about reading it than writing it & doubly so in fic, whereas in TV & books, it's more part of the general up and down of the thing, I suppose. Fic is usually shorter. I don't know. I think you can rationalise things so far and then it comes back to indefinable chemisttry of whatever it is again. :-)

Doctor Who does allow for an awful lot of variety - light, funny, it's a natural for crossovers, but there's plenty of room for angst and darkness right there in canon, too. So many characters, all the possible settings in the universe - it really is the most marvellous sandbox to play in. I love many other things, but DW is my forever fandom, especially when it comes to writing. I don't think there are any other fandoms where you have quite that extent of freedom while remaining perfectly canon-plausible.

Feedback does always help an awful lot, though!