Gaius: It's most odd. Look at this. See these two small wounds? Looks like a snake bite.

Merlin: How could he be bitten by a snake? He was injured in a sword-fight.

Gaius: His symptoms are consistent with poisoning. Slow pulse, fever, paralysis.

Merlin: Can you heal him?

Gaius: If it's a snake bite, I'll need to extract venom from the snake that bit him to make an antidote.

Merlin: What happens if he doesn't get the antidote?

Gaius: Then I'm afraid there's nothing more I can do for him. He's going to die.