the strongest steel comes from the hottest fire
By the time he gets into the building, it's already filling with smoke. Inside, it's chaos, people screaming, crying, fleeing with children and other precious things bundled in their arms. He's only been here once before, but he can find the stairs just by fighting his way upstream. Four floors to her apartment, and at every step they want to drag him back down, out to safety.
The smoke is worse in her hall, lit to hellish orange by the flames beginning to lick their way out of her apartment. If he was panicked before, he has no word for what he is now. If she was in there, she's gone.
He hears her name, and can't quite process that it's coming from his own throat. And then he realises that what he's looking at, covered in soot and ash and bits of debris, is Kate herself, crumpled against the wall just outside her door.
She doesn't answer when he turns her over, and for a moment it all falls away, the roar of the flames and the screaming chaos downstairs and the sirens signalling help is already on the way. There's just his heart, pounding in his ears, behind his eyes. And then, miracle, her hand twitches, and one foot, and then she's blinking up at him, disoriented but aware. Alive.
'We have to go, Kate. Can you move? Can I move you?'
There's blood on her face, in her hair, and a long gash down one arm. Bare. Her arms are bare, and her feet and he realises that she's completely bare apart from what seems to be a large bath towel. He shrugs quickly out of his coat. 'We need to get out of here, Kate. Are you hurt?'
She stares at his lips, uncomprehending. 'I can't hear you, Castle. I can't hear anything.'
As if on cue, they both start coughing and that's it. She's out of whatever small amount of energy was animating her this far, and he's out of time. He shoves aside the debris and wraps his coat around her as best he can. And then he gathers her up, praying there's no injury he's making worse, but walking out of here on bare feet isn't going to be an option even if she wasn't already beginning to fade away.
By the time he's staggered his way to the ground floor her eyelashes have fluttered closed and her body has grown so heavy he's nearly dropped her twice. And still, when he's met at the entrance by the firemen on their way up, and one offers to relieve him of his burden, still he's not ready to let her go.
With thanks to JC for the inspiration, and the title