Cas's angry voice stopped abruptly as Sam returned to the dungeon. Dean was smiling smugly, though the tautness of his jaw and the set of his shoulders betrayed his anger and unease.

Sam's chest puffed out as he took a deep breath. "You ready, Cas?"

"Ready," the angel said as he handed Sam the Anam blade, hilt first.

"Oh come on, Sam!" Dean groaned. "We've been through this! That fancy pig-sticker isn't going to magically" – he waved his bound hands satirically – "make the cure work – you already know it's a dud. C'mon, man, why bother?"

Sam ignored him. "Hold him down, Cas."

As Cas braced his arm against the complaining demon, Sam clamped a hand firmly just above Dean's bound wrist, noting as he did so that it was no longer broken. Courtesy of Cas, no doubt. The Mark of Cain cast a tiny shadow against the pale skin as Sam twisted the healed arm, forcing the brand to turn toward the ceiling.

As he gripped the hilt of the Anam blade more firmly, Sam took another deep breath, letting it whoosh out of him in a gush.

"This is gonna hurt, Dean," he warned, not lifting his gaze from the ugly symbol on his brother's forearm. Dean spat out a probably smartass response, but Sam wasn't listening. He needed to concentrate. What he was about to do could not be undone. Not with this blade.

Holding his brother's arm tightly, Sam placed the point of the ancient knife to the right of the first curved island of the design, about an inch away from the raised skin of the Mark. Angling the blade carefully, Sam pressed – hard. He felt the muscles in Dean's arm shift as his hand curled into a tight fist. Blood swelled around the tip and trickled down Dean's arm and the demon snarled in pain. Keeping his hand steady, Sam drew a deep diagonal line through the Mark, ending it several centimeters beyond the bottom left tip of the brand. Ignoring Dean's cursing, Sam drew an identical line from the upper left corner of the Mark to the bottom right, forming a bloody top-heavy X through the skin.

Dean began to fight against Cas's iron hold as the Mark began to burn a bright orange-red. His stomach churning unpleasantly, Sam drew another deep line of red, connecting the top of the X across the Mark of Cain. The Mark burned more brightly, like an angry coal. Dean thrashed in earnest, snarling and cursing as Cas held him tightly immobile.

Holding his breath, Sam connected the bottom left tip of the X to a point centered directly above the flat top of the Mark, then quickly mirrored the bleeding cut with the other bottom of the X, finishing the five-pointed star. The Mark's burning light shifted slightly under the leaking red lines, like lightning shifting behind storm clouds in slow motion.

Dean howled. The sound cut through Sam as easily as the knife cut through his brother.

Determinedly not looking at Dean, and carefully tuning out whatever words he spat so viciously in Sam's direction, he tilted the Anam blade again and made one final, deep cut. Blood beaded and flowed in a circle that connected the five points of the star.

There, Sam thought, straightening as Dean's head thrashed from side to side in obvious agony. A perfect miniature Devil's Trap.

Still studiously not looking at Dean, Sam gestured to Cas. "Okay, Cas. You're up."

Sam came to stand beside Cas and replaced his arm holding Dean back against the chair as the angel took Sam's place at Dean's side.

"You remember the words?" Sam queried.

Cas nodded as he pulled his sleeve up slightly to free his hand. Unlike Sam, Cas glanced at Dean as he laid his hand over the demon's bloody forearm, steeling himself. The angel closed his eyes as he began reciting the spell in perfect Enochian. The celestial words wove their singular magic into and around the deep cuts. A warm light glowed from under Cas's palm.

Dean bucked under Sam's arm, his head pressing hard against Sam's shoulder as he screamed. Sam closed his eyes, wishing he were deaf. Unable to block out his brother's pain, Sam focused minutely on the sound of Cas's voice weaving the containment spell. When he judged Cas was nearing the end of the incantation, Sam reopened his eyes and watched the angel's hand. A deep, bright orange-red light was seeping through the blood and flesh, shining under Cas's firm grip. The warm white light tinged with palest blue rose from under the angel's palm, fighting for dominance over the Mark's bloody gleam.

As Castiel's voice rose, adding power to the final syllables of the spell, his light intensified, obliterating the Mark's. Dean jerked sharply in Sam's grip and his head fell forward onto Sam's arm and he stilled.

Cas took a step back, staring uncertainly down at his bloodied hand. Sam cautiously drew back from the unconscious Dean and came to stand beside his friend. He clapped a hand on Cas's back.

"Good job, buddy. That's step one done."

Cas returned Sam's feeble grin. Together, their gaze turned to Dean's right forearm.

The bloodied Devil's Trap was no longer red and bleeding. Each line Sam had carved now bore the pearly-white appearance of old scar tissue. The Mark retained its reddish colour, but it was now held captive in the engraved Devil's Trap. The Enochian spell had also added another element: the circle enclosing the star and Mark was now wreathed in that looked like whitish flame, making the symbol lying over and through the Mark of Cain look like a wilder version of Sam's tattoo.

"Is that it?" Cas asked quietly.

Sam compared the two brands to the image Death had imprinted in his mind. "I think so. It looks right, and we did it just the way he said to."

"It just seems too ... simple."

Sam's eyebrows rose. "I know what you mean. But I trust Death." He frowned briefly at the absurdity of that sentence. "That should contain the Mark's power and stop it affecting Dean."

"Should?" Cas repeated skeptically.

Sam shot him a glance. "Yeah, should."

Cas leaned forward, inspecting Dean. "Do you think he's alright?"

Sam sighed. "I sure hope so. There's a long way to go. It's only gonna get worse for him."

"Speaking of." Cas sighed, picking up two syringes from the table and handing a plastic one to Sam. "We shouldn't delay."

Sam took the syringe with a curt nod. "You first."

Cas rolled up his left sleeve and sunk the tip of the large syringe into the crook of his arm. As he pulled the plunger back, swirling blue-tinged Grace flowed into the waiting cavity. He extracted the tip and stepped forward, closer to Dean.

"Grace of the angel ..." he muttered to himself as he pierced the skin of Dean's neck and pressed the plunger all the way down.

Dean twitched and shivered as the Grace thrummed through him, but his eyes stayed close and his head remained hanging over his shoulder.

Cas looked to Sam. "Your turn."

Sam copied Cas, drawing his confessed blood into the syringe.

"Blood of the brother," he heard himself saying as he injected it into Dean's unbranded arm.

Dean's eyebrows twitched and his arm shivered slightly, as though trying to dislodge a fly.

Sam looked down at his watch, marking the time.

"One."