Jack was stuck firmly between fight or flight, with an adrenaline rush that was making his head spin. He closed his eyes when John told him to, jerked back away from the strap pulling tight, just a little, and coincidently moved toward John.
As soon as he couldn't see he got tipped that much further off balance, his heart rate kicked up that little bit more and when he was tapped he turned toward it, immediately. The hand under and on his was a good thing and when he got off his knees and stood there was a definite lean into John; he didn't trust his own balance.
This was scaring the ever living fuck out of him, he realized, but he was still physically responding. He was too focused elsewhere, fighting down the increased urge to anticipate to pay much attention to it, but the fear and situation and idea and John's voice had him hard.
"Where am I going?" His voice was deceptively steady. He wasn't shaking - quite- but there was a very, very, faint tremor there that was... the threat of really starting to shiver.