I just had an idea, listening to a talk about the future of computers. Supposedly we will, at some point in the future, by use of special contact lenses, be able to view a modified version of reality. Well, take that, and couple it with something like the relationship between Gaius Baltar and Six in Battlestar Galactica, and you've got the basic idea. Don't worry, I'm going to explain.
Basically, it would be set in a future where augmented reality of a far more advanced sort than a simply overlay of information is a simple fact of life. It's so advanced, in fact, that you could create a virtual person who - aside from not existing except as a figment of your imagination - is indistinguishable from the real thing. Touching that person would feel like touching a real person. You'd be able to have conversations, feel their breath, and so on. Of course, it's all under your control, so it's never quite real, always, on some level, fake.
Here's what I have in mind: my character, a reclusive programmer, perhaps a pioneer in the field, creates for himself an ideal woman. Because it's all virtual, there are no limits as to what that could entail. It could be anything from an alien creature, a half-animal, or a person from a distant historic period. I lean toward the last example, but I'm open to suggestions here. It doesn't quite end there, however. What happens is the program, that is to say the virtual person, by some accident - a virus, some sort of mechanical malfunction - takes on a life of its own. It becomes, in essence, a real, imaginary person.
Well, there's the idea, anyway. If it sounds interesting - or confusing - let me know!