TVTropes has just told me what vocaloids are. And I am hilarified. Why?
Because of
this.
In 1996, William Gibson published Idoru, set in his crazy future-Japan. (Of course.) let me quote:
"But do they really have singers that don't exist?"
"The idol-singers," he said [...]. "The idoru. Some of them are enormously popular." (Gibson 57)
Idoru, in Gibson's novel, are people/personalities that exist only in digital space, putting out songs and records, cooperating with meatspace people to form bands, and etc and etc and etc.
"Do people kill themselves over them?"
"I don't know. They could do, I suppose."
"Do people marry them?"
"Not that I know of." (57)
Of course, real life isn't quite like that, and of course, constructed personalities aren't exactly the same as living personalities -
- but still, it's a fascinating idea. Life Imitating Science Fiction.