Go ahead and write it. Whether anybody else might want to read it should never be a barrier; otherwise all kinds of things would never have been written. As to the other thing - well, that depends on where you're planning to display it, if at all. I'd have thought that LJ would be fairly safe, unless it's Jesus/St John the Baptist slash, or something. And even then, I doubt you'd be the first to have written it. This is LJ!

Besides, lots of people have to read something before any real kind of a fuss is made. And again - this is LJ. It's not prime time TV, with an audience of fifty million.