That's not corny at all. I've written several short stories about my longest-running D&D character -- not for public consumption, though, mostly just so my fiance, who was DM'ing that game, could get a feel for how I pictured my character and his NPCs.
I was writing about and for the game, though, so I couldn't change "canon" as one could when writing a book inspired by a game, and I really felt the pinch.
As long as it's a good, solid story and you can be objective about your PC (I never can!) I think the built-in history will just make for a better novel.
