It's a series of seven of Clark Kent's dreams/nightmares. Lex is a prominent figure, but this isn't necessarily slash. This reflects a much deeper aspect of their relationship and Clark's relationship to the world:
They hold up a mirror to his face, and when Clark looks at it he sees a giant bug's head, like an alien invader in an old black and white movie.
"Thank God," he says, more relieved than he's ever been in his entire life. "Now I'll never have to pretend to be human ever again."
Just a warning, there's some stark and violent imagery in this one. But if that intrigues you, like me, go and read.