It took something like eternity, but they crossed purgatory and broke free. They found the scar tissue left from raising Eve, left from Cas cracking it wide open for power, and punched right through. Cas tore a hole in the world a second time, exposing something in-between that made Dean feel like his mind was coming apart at the seams when he looked too closely at it, and braced it with his wings. He arched them high and kept the gap open wide enough for Dean to slip through the passage and out the other side.
“Cas, c’mon,” Dean rasped, reaching a hand back when the angel didn’t move.
Castiel shot him a panicked look, shaking with the effort of holding the edges of the world apart for him, and Dean’s heart dropped. Castiel looked exhausted, looked resigned – Dean could see the hope dying in his eyes, could see the decision on Cas’ face like he’d seen it on Jo’s, on Ellen’s, when she made that final stand for them.
“No,” Dean snarled, shoving past his own exhaustion and stepping back inside the breach. “No fuckin’ way, Cas.”
“Dean,” Castiel choked desperately, pleadingly.
Dean caught a glimpse of the inside of his mouth as he spoke – all slick, dark red as blood welled up in his throat and spilled over his tongue. His teeth were stained with it, his lips turning scarlet as it overran and poured down his neck, staining the filthy neck of the once-white hospital shirt he still wore.
“I’m not leaving you here. You pulled me outta Hell, Cas, an’ kept my stupid ass alive through the goddamn apocalypse. You pulled Sammy outta the Cage, and beat Raphael and faced down Lucifer and called Michael an assbutt, for fuck’s sake. You kept me alive in purgatory,” Dean said, fisting a hand in the lapel of Castiel’s trenchcoat. “Come on, this should be easy after all that, right? One step at a time, Cas. You can do it.”
Dean heard something snap and Castiel moaned in pain, trembling violently. Dean spared a moment to feel deep, profound grief at the idea of his angel’s wings being broken, being ruined, and all for his sake – but then he steeled himself. Better Cas have broken wings than be destroyed in this in-between place.
“One step, Cas,” Dean coaxed, taking one backward himself, tugging Cas by his trenchcoat. “Just a step.”
Castiel took a tiny staggering step forward, eyes wide and fixed on Dean as the passage shuddered dangerously around them. It was everything and nothing like watching Sam take his first steps – he was proud and terrified all at once, just like he had been then, but Cas’ eyes were starting to tinge red with burst blood vessels, blood leaking from his nose and ears. Dean didn’t dare look away to check his wings, but every few seconds he heard another crack or snap and a pained grunt from Castiel.
The passage suddenly narrowed, and Castiel froze.
“One more,” Dean begged, hands shaking as he tightened his grip on the angel’s coat. “Cas, please.”
“Go,” Castiel ordered, the word almost lost as he coughed up a mouthful of blood. “It won’t hold.”
“Yes it will,” Dean snapped angrily. “Now take a fucking step you stupid, feathery asshole!”
Castiel made a hopeless sound that might have been a laugh, sliding forward another agonising inch almost like he couldn’t help but obey. Castiel screamed, a loud crack echoing through the dead space they occupied, and Dean felt something in his chest ache at the sound – but he didn’t stop, didn’t dare stop.
The passage had taken Dean a heartbeat to cross the first time – barely five steps – but leading Cas through felt like crossing purgatory all over again. He could feel the warmth of earth at his back, the ice-cold of purgatory slowly growing distant – but the edges of the crack they’d punched open were beginning to scrape in. Dean could feel them against his shoulders, the gentle pressure knife-sharp through his clothes.
They weren’t going to make it.
“Trust me, okay, Cas? Just trust me.”
Castiel nodded blindly, unable to speak. Dean took one shuddering breath, tightened his grip on Cas’ coat, and threw his weight backwards.
Something tore through his shoulder, wringing a scream out of his lungs as pain unlike anything he’d ever felt shuddered through his body. Dean had held his brother as he died, had been torn apart by hellhounds and dragged to hell, had tortured and been tortured by the best Hell had to offer – and nothing compared to this. He went blind and deaf with it, unaware of anything but the pain and, distantly, the sound of purgatory slamming closed with a sound like the world ending.
When he came back to himself some interminable time later, he was lying on his back, staring at the first blue sky he’d seen in an eternity. His shoulder was cold and numb, and he could smell his own blood, could feel unconsciousness creeping in on him, but the sun was warm on his face and Cas was sprawled on top of him. He was exhausted and aching, and Cas was gasping, wings sheared off and bleeding, but they were alive and finally safe.