"I'm not being tricked by this fucker," John insisted as he kept the gun firmly against the Doctor's head. Hey, he'd had radiation sickness before and hell, if he was going to die because of these two then he was at least going to make a mark. Adding pressure and taunts to John when he'd under stress was perhaps the most unwise move anyone could make, it always made him a little more impulsive.

John was at heart a gambler. "You're trying to get into my head, aren't you? I know it. I'm not a idiot. Suggesting symptoms so I feel them? Oldest trick in the book, mate. So here's the easiest way to prove it to me, prove that I'm being radiated. Fix my bit of kit here and I'll be able to detect the radiation." John said as he shoved his arm out a little further so the Doctor could take a look. Maybe do whatever zappy thing he did with that blue wand he had. "If you actually give a shit about me and you living through this then fix it? If you don't, we die together. Seems fun, right? Death! Exciting. Never done that before."

John let out a nervous but reckless laugh with anything but a stable smile on his face. Dying was terrifying but dying while he took someone with him he didn't like? Seemed like a fitting end. "Come on, times a'ticking. If I'm going to die, all these moments are very precious."