The urge to tense as Steve's hand moved towards the reactor was completely instinctive, but Tony found himself taking a sharp breath as the fingers hit his skin. Instead of the half-expected panic, it was just heat and something that felt almost like comfort. And then Steve was touching the mark on his wrist and Tony was just gone, swept into a feedback loop that obliterated every thought he might have had.

When the contact broke and the world came back, Tony found himself breathing hard and a quick glance over proved that Steve didn't look much better. There was something comforting about that, that after all this time it wasn't just him anymore.

"It's. Uh." He licked his lips as he tried to pull his thoughts back together. "Like a very fancy pacemaker? It's keeping my heart beating." Too scrambled to deflect. That probably said everything.

He couldn't bring himself to regret it, though. If anyone should know, it was probably his soulmate.

"I have. Shrapnel. In my chest. This," he waved a hand at the reactor, "powers an electromagnet that keeps it all from moving."