Dean_the_Young wrote...
On the other hand, if you make an OC and attach him/her to familiar cast, it looks too much like a self-insert, and the OC tends to dominate certain areas like a Sue. I have musings, for example, of a mercenary crossbow sergeant sent from the Free Marches to help the Warden: his approval is more dependent on those Big Choices than anything else, and by the end his attitude can range from unbreakable loyal supporter (if you make all good choices) to actually turning on you at the last choice (to stop you from dooming the future).
But while I might muse, I would never inject him post-action into Origins, because it strikes me as trying to usurp everthing else.
OCs can be tricky, and to some extent I agree with that. Although, really, ALL Warden characters are, if you think about it, OCs.
A lot of postgame stories have bunches of OCs that work. I'd like to think mine don't come across as self-inserts since there's dozens of them, the only ones who get any degree of major story time all have pretty distinct backgrounds, personalities, and qirks, and I don't (to my knowledge) have multiple personality disorder.

More than a few readers have commented liking them, or actually have favorites among the OCs, so I guess I was successful to at least some degree.
I had OCs in my blight story as well, but I tweaked the beginning by including more time in the tower, (so I created other mages and apprentices my Warden was friends with, since, you know, seeing them all slaughtered when Uldred goes mad will be a nice character-building/brain breaking experience for her) and making the trip to Ostagar and the length of stay there longer (so there was a realistic timeframe for Jowan to get caught and do his thing in Redcliffe), so I made other Wardens (well, names and personalities for the three other wardens shown with Duncan in the dwarven noble origin), an Ash Warrior she hooked up with in a tavern on the road there, and so on.
But creating a brand new party member from thin air? I wouldn't do that. The closest I'd do would be an AU story combining origins or recruiting someone who already existed with at least a somewhat defined character. Having Daveth survive, recruiting Jowan, etc. I'm sure someone could do it successfully, and probably has, but I think putting someone completely new into established situiations like that would be dancing a bit too close to the Sue line for my own comfort.