Anthony Edward Stark

Tony catching him was helped by Steve slamming doors open as they passed. He wanted to make sure there were no other prisoners but also that there weren't any guards that we're going to pop out and flank them.

When Killian turned to face him, Steve realized he either used this extremis thing on himself or had abilities of his own.

"He's enhanced!" Steve shouted, twisting to protect Tony from the blast that erupted from the man's hands and when he hit the shield, Killian opted to drop the ceiling on them instead.