Oh, and I should apologise in advance that most of my examples relate to Colin. But, you know… obsessed Colin!nut here - like you didn't know that already!
 We're still writing about characters. It has always been very clear to me that we're reading and writing about fictional characters, even though they're based on real people. (I suspect that some people who disapprove of RPS don't think we even see the distinction.) Despite all of which, it quite startled me when I first Colin and Bradley in the flesh… (Sorry, just talk amongst yourselves for a while. Normal transmission will resume shortly.) Right. It quite startled me when I first Colin and Bradley in person that I immediately felt, 'That's not them!' As in, that's really not who I write about. So there are certainly layers of identity - Merlin and Arthur, the fictional RPS Colin and Bradley, the public Colin and Bradley, the private Colin and Bradley - at the very least. Despite me knowing I'm working with characters, though, I do treat Colin and Bradley differently - more carefully and respectfully - than I would treat Merlin and Arthur.
 Details of family and friends. My feeling is that these sorts of things should generally be left alone, with a couple of exceptions. Colin himself has mentioned his brother Neil a couple of times, and Neil has appeared with him at at least one event. Hey, Neil is even gonna be an extra in Merlin. That puts Neil in 'the public domain' as far as I'm concerned, and I feel free to write him in as a minor character. When it comes to Colin's parents, however, we only know a few very broad details, and I feel we should leave it at that. Colin obviously cares very much about his mum (aw…) so if we're writing realistic fic, then it would be odd not to take that into account if it's relevant to the plot or characterisation. I would always leave the details vague, though. In a comic story, however, I would feel free to introduce them in more detail - as long as it was fairly clear they are being presented as the sort of caricature you would find in any comedy. My own a bit of nonsense for sezso and ifyouweremine's Wherein Colin is Bradley's Baby Momma spring to mind as examples. We are assuming a certain 'true' background, but otherwise clearly writing the characters as suits our own comic purposes.
 Big Dramatic Traumatic Topics. I'm talking serious things here like rape, murder, incest, abuse, what have you. I would feel free to read and write about these topics in relation to Merlin and Arthur. I would be a great deal warier about them in relation to Colin and Bradley. Partly because, well, the Merlin universe features violent deaths every week, so it's already part of the canon. Partly because Merlin is fantasy and a kids show, while RPS is set in the 'real' world. I'd expect it to be handled far more seriously.
 Personal facts or fancies that are controversial. From time to time real issues arise - such as Colin's weight and whether we think he's healthy or not - and create some controversy even in discussion. Personally, I would only ever approach such things in what I consider to be a positive way. With Colin's slimness, I deliberately present him as healthy (a good thing) though I also let Bradley fret over it a bit (acknowledging there is a potential issue). I feel that's a responsible approach - however, I also realise that anyone who thinks he has a serious problem (i.e. an eating disorder) would instead think I was being irresponsible in treating the matter as a good or at least acceptable thing. Again, I would feel free to treat such difficult personal issues in a far broader way within the Merlin universe. If I thought Merlin was completely co-dependent and or was being corupted by his power, I would feel free to explore that positively or negatively or any damn way I thought it worked. Not so with RPS!
OK, so that's me feeling my way around a few ideas. Over to you! I'll be fascinated to read your thoughts and reactions.