It did hurt. It hurt a lot. And, before he realized quite what was happening, it suddenly hurt to breathe. His lungs felt tight and heavy, like he was taking in water. Like he was back underneath Torchwood Three, near-drowning.

He gripped Jack's arm, his eyes wide with panic.

This was the drug, right? Okay, so it was making him immobile, taking away his ability to breathe, but it wouldn't kill him, that was far too easy. Maybe kill him if he didn't stop it, just to see if he could? He didn't even know what they could've used!