From an spn_blindfold promt : When Sam feels tempted by demon blood or self-loathing, Castiel paints sigils and symbols of peace on his body to calm him. If there's sex, have it be gentle.
It started during his second detox in the panic room. Castiel was the only one who could sit on the other side of the iron door and listen to his screams. Castiel would come in and leave bottles of cold water, empty the pail of vomit, and wipe down his forehead.
He could barely choke out a thank you to the falling angel every time he did this. He started to doubt his initial thoughts that Castiel hated him, was disgusted by him. Cause if he did feel that way, why was he taking care of him?
On the third day in, Castiel entered the room holding a bottle and a small brush. Weak and desperate, Sam was curled up on the tiny cot. He couldn't find the words to greet Cas, or ask what he was bringing.
"It will not take the pain away," Castiel said as he sat on the cot beside Sam. "But it will help soothe your mind."
Sam couldn't protest. He was so exhausted and raw he didn't even fight when Castiel carefully removed the sweaty shirt from Sam's chest. He eased Sam onto his back.
The metallic tang of blood hit Sam as Castiel unscrewed the bottle. But it was different. It wasn't demon blood. There was something gentle and comforting hiding under the heavy smell.
"It's dove's blood," Castiel offered. Castiel dipped the brush into the bottle and touched the bristles to Sam's sweating heaving chest.
Castiel sang softly in Enochian as he made small strokes of the brush. Sam closed his eyes and let the gentle words and brush strokes cover him.
"whachadoin," Sam mumbled.
"I'm painting symbols of peace," Castiel said, resuming the soft singing.
Sam fell asleep before Castiel could start on the third symbol.
Sam never got over the irony of using blood to help soothe the war in his mind over his demon blood addiction. He also never understood how Castiel managed to know when Sam needed it. Sam wouldn't say anything, but Cas would stand there, bottle and brush in hand.
The songs Castiel would sing changed, but the various symbols and sigils were always the same.
Tonight, Sam was hit with self doubt. It seemed that nothing he has ever done, or will ever do will help him atone for this. He's curled in the corner of the closet in their motel room, near tears.
He heard the familiar flutter of Castiel coming into the room. Without words, Sam uncurled himself and crawled to the bed. He shrugged off his shirt and hung his head. Castiel kneeled on the bed behind him, opening the bottle.
Castiel placed a chaste kiss to the back of Sam's neck and sang onto his skin:
Im nin'alu daltei n'divim
Daltei marom lo nin'alu
El Chai, mareimawm al kawruvim
Kulawm b'rucho ya'alu
A silent tear escaped Sam at the Hebrew words he didn't understand. Castiel repeated the verse as he painted the various symbols on Sam's back, feathering kisses beside them.
Castiel straddled Sam's lap and brushed his hair off his forehead. Castiel placed a kiss on the center, the place the angel would touch when he used his grace.
Sam wound his arms around Castiel's waist and rested his forehead against Castiel's.
"Thank you," Sam whispered against chapped lips. Castiel pressed their lips together. Sam threaded his fingers in the unruly black hair and deepened their kiss.
They fell back onto the bed, kissing softly.