The X-Files, Season 2

Mulder:
It's a stiff price, though. Look at yourself - drinking blood, living in darkness, unable to see your reflection in a mirror. Or is that just a myth?

John:
I can't be seen in a mirror. Look… anything worth anything has a price and when I'm standing next to your deathbed looking as young as I look right now and I see that fear in your eyes at the moment of death … then, then tell me the price is too stiff.

Mulder:
It's more likely I'll be looking in your eyes at the moment before they lead you into the gas chamber. That's a moment you won't have to face if you tell me where the others are.

John:
Why would I? They're the only ones that can kill me.

Mulder:
Well, if you are what you say you are, I know what can kill you.