The name given to the male of the over-perfect self-insertion is Gary Stu. And they're not at all uncommon. Alas.
I think 'Mary Sue' stems from a particularly notable early example of a Star Trek fic.
Drakensis, I think you are on to something here. Short stories of what if could send our minds into the twilight zone without actually rewriting all the future consequences. It sounds compelling to leave the consequences to the imagination thereby not completely destroying our favorite cannon while at the same time provoking things aren't what the should be feeling. I'm intrigued, write on. Although, please don't mind if I tell you, I will shy away from wholesale mass murder. If you could keep the death count down, then I am reading on.
I'll give it a little more thought. The scenario I'm thinking off isn't quite coming together yet. However, another possible scenario does present itself.
Some "what ifs" are not worth pursuing, though. I always wondered how it would have been if Kevin and Bronwyn had lived, only to realize that Kevin would probably have been hung beside his father in HD.
Can you imagine Duncan and Morgan's rage at that?!!?
Well at least poor Bronwyn would have survived. And they might have a niece or nephew.