Sam was blown back by the force of the white light that was bursting out of Castiel's body. He slammed hard into the far wall of the dungeon and slid in a heap to the equally hard ground.
The light was more intense that any he had ever witnessed. It seared his retinas through his closed eyes, so he shielded them with raised forearms, but it did little to help. A high-pitched, painful ringing accompanied the impossibly bright light, so loud it drowned out Castiel's agonized scream.
Sam curled into a ball on the floor, trying to protect himself. The light beat against him like a physical blow, pulsing out from Cas in an ever-increasing rhythm, like a panicking heartbeat. A scream of his own wrenched itself from Sam's lungs, but even he could hardly hear it.
He trembled as the light consumed the world.
As suddenly as the explosion had started, it stopped.
Sam lowered his arms slowly, breathing deeply as he squinted, the imprint of the brilliant light superimposed over his vision.
Cas was on his feet, standing in the centre of the Anam sigil. The lines of red paint had been mostly burned away, leaving speckles glowing like embers, hinting at the symbol's original design. All traces of blood and dust had disappeared from Castiel's clothes. His skin had a healthy glow and the dark circles under his eyes had vanished. His hair was ruffled, windswept from the force of the spell. His pupils shone with the electric blue Sam had seen before, though it had never looked as bright as this. As the light faded, Castiel's eyes were alight with joy and calm, the corner of his mouth quirked in a miraculous smile.
Cautiously, Sam rose to his feet. "Cas? You okay, buddy?"
Cas looked up from his healed body to meet Sam's gaze, his face positively shining with wonder. "Sam ..." He gestured to himself, at a loss for words. Glancing over his shoulder, he beamed.
"I, uh, I made you a new Grace."
"I can feel that ... but ... how?"
"Death told me."
"Death!"
"Yeah, he said it was one of the oldest spells in existence. He wasn't sure why God made it."
Cas gaped. "What was the spell? I didn't think such a thing was possible. Least of all by a human."
Sam snorted. "Thanks."
"I-I mean," Cas started, backtracking. Sam held up a hand, smiling as he strode forward to embrace his friend.
"Good to have you back, Cas."
He felt Cas's arms tighten slowly around his middle. After a moment, they broke apart.
"But how did you do it, Sam?" Cas asked, his eyes still wide. "It ... it ... feels so different from my Grace. From any angel's Grace. It's ..." He searched for the word, his eyes roaming around the dungeon as though hoping to find it painted on the walls or ceiling. "... warmer."
"It that a good thing?" Sam asked uncertainly.
"Good? Sam, it's euphoric."
Sam broke into a wide grin.
"How did you do it?" Cas asked again, more insistently.
"It was actually kind of easy. Well, there were a load of ingredients I've never even heard of, but the Men of Letters clearly had: everything I needed was in their storerooms. But the ingredients were more sort of ... decoration, really."
"Decoration?" Cas scoffed. "Then what – how – Sam! A Grace! That's pure creation!"
"Exactly," Sam said, smiling.
Cas's expression turned from exasperation to puzzlement. Taking pity on his newly angelic friend, Sam explained.
"Grace is pure creation, but it's not the only thing on Earth that is. The spell Death told me just showed me how to harness that power that was already there and throw it your way. And it's like any angel's Grace: infinitely renewable."
"It's not like any angel's Grace, Sam, I can assure you. This feels far stronger. What power did you harness? Sunlight?"
"No, no." Sam chuckled. "Human creativity: imagination."
Cas's smile widened. He stared at Sam in amazement for a moment before throwing his head back and roaring with laughter.
Unable to stop himself, Sam joined in. "What's so funny?"
Regaining control of himself – barely – Cas managed a signal word. "Winchesters!"
As Cas was swept up in another wave of loud guffaws, Sam's smile began to fade. When Cas glanced at him, he made a show of laughing along, but inside he felt himself settle back into a determined, if sorrowful, calm.
When Cas had finally laughed himself out, he put a hand on Sam's shoulder. "The day will never come, Sam Winchester, when I am not amazed by you."
A small smile twisted the corner of Sam's mouth, and he glanced away, touched.
As Cas's chuckles died away, his eyes turned to the iron Devil's Trap on the floor. "Death told you of the spell you say."
"Yeah."
Cas lifted his gaze to meet Sam's. "Did he tell you any others?"
Unable to smile, Sam nodded. "Just one."
"Do you have everything you need for it?"
"Almost," Sam replied. "There's one last piece I need."
A/N: 'Anam' is the Irish word for 'soul'. I'm Irish and couldn't resist adding some Celtic mythology and Gaeilge :) Many thanks and hugs to my readers and reviewers, hope you're all enjoying the scéal (story)! Author out!