A girl grows up in a orphanage and her only possession is her teddy bear. He's her best friend in times she has none and that's because he's alive. No one knows this, but her. She grows up and goes to college, taking her bear with her. As she grows and matures, the bear starts to see her differently. Often times, she wakens with the bear between her legs and she's in the throes of orgasm.
Our story picks up while she's in college and the bear begins to become more and more dominant with her, becoming essentially her master.
The details can be talked out and we can include a male taking interest and the bear of course not liking it. I'm open to include other ideas as well.