I'm sure I'm probably just missing it, but has this been discussed? Who are the three death eaters at hogwarts that voldywart mentions in book 4? Do they necessarily mean who we think they mean?
The faithful one who returned: Naturally we assume that this is the Imposter Moody (Crouch, Jr). However, we never really know if he was an original Death Eater, so, assuming he wasn't, why would voldywart say he's a faithful death eater who's
returned to his service? Karkaroff was
definately not faithful, so we throw him out. If Snape is a good spy (voldywart doesn't know he's a double agent yet), then Snape would be the faithful DE already back in voldywart's good graces (think like Voldy, not like a member of the Order).
The one we believe has left and must be killed: We assume upon first reading that this is Snape. But if Snape is the faithful one, who is this one?
The coward: Karkaroff. Almost sure of it.
NOW... Assuming Voldy doesn't know that Snape's a double agent, and therefore the faithful one, and Karkaroff is the coward, where does that put Crouch? And if we take this route, then that means there's
someone else at Hogwarts.
My brain's tired...