It's not that I'm uninterested in the "big 6" -- I've read everything I've been able to find in the LFN fanfiction world, and have enjoyed seeing the different perspectives on those people. But as I read, I began to think of Section itself as an additional character -- not in a science fiction-y way, but as a living environment that would look and smell a certain way, and have a specific affect on the people who lived and worked there. I am a fairly practical person in the real world, and so when I write that tends to bleed over into the stories -- I like to think about how stuff works, and who might be involved in its workings. And while I do think of the main characters as motivators for plot, there are so many other people who are affected by their actions -- I enjoy thinking about their stories, which means that I often have to manufacture people.
I don't really think of this as making Marys or Garys -- most of the people I've written about aren't anywhere close to the paragon nature that I understand the Sues and Stus usually have. But I have read stories with strong characters that occupy a significant piece of story real estate (the Becky Moran character that's been mentioned above is an example) -- I like thinking about how someone else might function in that role, and I like the additional perspective on the environment (and on the main characters) that you can get from that kind of OC.
Like many of us, my eyes have rolled a bit when "supergirl" shows up with all her signature qualities (smart, sexy, sartorially perfect -- not to mention the hair), but even at her Mary Sue-est, she can be another window into a world that I still find bizarrely fascinating, so I keep on reading.
