Written before Utopia was aired, but I think it still makes sense despite the mystery being take out of the whole thing. Ususal stuff, I don't own the Chronicles of Narnia or Doctor Who - that's people more fortunate than me. This is just for fun... :-D
"Greetings, Jack, Son of Adam." The great lion rumbles in his deep resonating voice.
"But am I really?" He can't help but ask. "Even now?"
Aslan stares at him with his great golden eyes for so long Jack begins to regret asking the question.
"Yes." He says finally. "What ever else may befall you on your path in life, you are still human. I doubt anyone is supposed to live forever, even you, Jack Harkness. That is a burden too great for any man."
"Even lions?"
Aslan looks at him, eyes twinkling, giving him the lion equivalent of a grin.