I write in the Battletech universe, 13 stories published so far from the Battlecorps.com website and hopefully more to go.
I have a hundred or so books for the Battletech universe, both in DTF and eBook that I can draw on for people, places, and items. The universe is a live one, moving forward in time (3085 right now), yet going back and filling in details that had been mentioned but not explored.
States rise and fall in fortune, and major things happen (The universe is coming off a massive war that was started by a bunch of tencho fanatics that wiped out a number of planets, destroyed dozen of units, killed major characters and shook up the status que.) But the constant is that warfare exists and the Battlemech is the king of the battlefield.
But Battletech has always been about the characters, and with the wide number of groups and backgrounds, there's all type of characters. For me, it's a matter of taking all that history, all that background, and crafting characters and stories that fit into that universe. For me, its one step in the direction of creating my own universe -- All I have to do is create characters and stories. My background is already there, as the events I can play off of.
I am creating my own universe for my own stories, but for now, I'm going to stay and hone my craft in the battletech universe....
Craig