Sometimes, Jack wished that the Doctor would just shut up. John usually didn't take well to being so openly mocked. Still, he was usually better at this sort of thing than Jack was, and that was very much a saving grace.

"John... I'm safe. The Doctor is safe. Our bodies can handle it... Yours can't. Trust me when I say this, John, cancer is not a great way to go. Not to mention all of the other health effects it'll have on you." He took a cautious step forward, hands empty and raised. "If we hurry, we can help you. Your hair is much too pretty for you to lose."