Where Home Is: Science Fiction

When you know where I come from, you'll run and scream. But now you sit there, smiling at me so sweetly that I pray you never find out. But I know that you will; they all figure it out, in the end. It may take years, or in one case, even decades (she was sweet, but not particularly bright, that one), but one day they start asking questions: Why don't you look much older? Why have I never met your family? Why do you never really seem to need a job?

I've worked over the centuries to fit in better. I carefully brush grey streaks into my hair if I've been in an area for more than a few years, I hold down a job despite the entire lack of need for it, but still, some signs are only possible to mask.

Inspiration: Flogging Molly - "Laura"
Story Potential: Medium.
Notes: For some strange reason, this one sounds more like sci-fi than horror to me.