You could give the Seer ambigous traits so that one cannot actually interpret their gender. I mean it [i]would[/i] make sense for a Medium to have a sort of androgynous appearance, would it not? A person of great wisdom would not be bogged down with the gender norms societies impose on humans and it would add to the mystique of the character. Matters of identity wouldn't plague someone who uses their insight to the see what the future has in store. They could even go as far as to use different pronouns or speak in the third person to obscure their identity even more. But these are merely suggestions. :)