Cas dropped to the ground and Dean thought that his heart had definitely stopped. He swung out with his knife, hitting the witch he was battling in the side. She shrieked, but the wound barely slowed her down. Dean heard a gunshot followed by a thump, and figured Sam must have killed his witch. "Dean, move!" Sam bellowed, and he crouched down as Sam fired, the bullet hitting the witch in the back of the head.
Dean kicked the limp form away from him and rushed over to Cas, who was still lying on the cold cement ground. "Sam, help," Dean pled, and Sam rushed over to where Dean was crouched down. "What's wrong with him?" Dean asked, and Sam shook his head.
"I don't know. Castiel, can you hear me?" he asked loudly, shaking their friend. Cas snorted, but remained motionless.
"Cas!" Dean tried, and received a mumble in return. "What did he say?"
"No idea. It looks like he's...sleeping."
"Angels don't sleep."
"I know. But look at his chest." Dean glanced down and noticed Cas' chest moving up and down slowly, as if he were breathing deeply and slowly. "Feel," Sam commanded, bringing Dean's hand to Cas' wrist just under the base of thumb. Dean felt a steady pulse drumming under his fingers.
"He's human," Dean said in surprise. Sam nodded in agreement. "How the fuck...?"
"It must have been the witches." Suddenly Sam felt something hot and sticky on his other hand, and he looked down to see spots of dark liquid on his fingers. "Dean, look. Blood."
Dean squinted at Sam's fingers. "It's black." Dean ran through the fight in his head, trying to remember if he had seen something one of the witches could have done to Cas. He grabbed Cas' hand and that was when he felt it: a wooden spike that looked like a golf tee sticking out of Cas' palm. Dean yanked it out, causing Cas to moan in his sleep but not wake up, and examined the tip closely. "There must be something on this," he concluded. "Something that made him human."
Sam began to haul the angel up off the floor. "Let's get him back to the bunker and I can do some research." Dean nodded and helped his brother put Cas in the back of the Impala.
Arriving at the bunker, the brothers deposited Cas on Dean's bed while Sam wrenched open his laptop and started researching. Dean moved to sit between the headboard and Cas's body, letting the angel's torso rest on his own. He sat silently, monitoring Cas' breathing, for about ten minutes before Sam spoke.
"I found something." He brought it over to the other side of the bed so Dean could read the information. "Apparently this poison made from a witch's blood makes a non-human a human."
"For how long?" Dean asked, relieved that it wasn't something more serious.
"It doesn't say. It just says that the poison is deadly if not removed. Cause of death is blood buildup in the lungs."
"What?" Dean asked nervously. "Blood buildup? But how do we-?" He was cut off as Cas coughed violently and pushed on Dean's stomach to sit up. "Cas?"
"Dean," Cas coughed. "I can't...I can't feel my grace."
"I know, baby," Dean soothed. "That witch poisoned you and made you human. But we're working on it, OK?"
Cas tried to reply, but coughed wetly and spit blood up onto Dean's shirt. "I thought human blood was red," he commented, as if he didn't just spew the substance out of his mouth.
"It is," Dean said. Cas coughed even more violently, blood spilling out so fluidly it seemed as if Cas was vomiting it up. "Sam, do something!" Dean cried, sitting Cas up and pushing a trash can under his nose.
Sam pulled the laptop towards him and began typing frantically. "Dean," Cas cried, unsure of what he wanted but confident that Dean could give it to him.
"Shh, it's alright." He rubbed Cas' back and waited for Sam to find something.
"Dean?"
"What, Sammy?" he snapped as Cas continued to cough up black blood.
"I need to run out."
"No."
"I found something that will make this go away. I need to go get it."
"Where is it?"
"Twenty minutes down the road."
"Cas doesn't have an hour, Sam." Cas sobbed out in reaction to the statement.
"Well obviously I'm not going to follow the speed limit, asshole."
"Fine."
The door slammed shut as Sam sprinted away and out to the car. "Dean," Cas cried, finally able to catch his breath for a moment.
"It's OK, Cas. Sam will be right back and then you'll be all better."
"Dean, I...I don't know what I'm feeling. I feel sick and I...I can't seem to catch my breath, even when I'm not coughing."
Dean put an arm around Cas' waist. "It's called fear, Cas."
"It's very uncomfortable," he managed before coughing into the trashcan again. Dean laughed and kissed Cas' temple, trying his best to soothe him.
Fifteen minutes after Sam left he was back, holding what looked like an old school medical bag that doctors brought on home visits. "You get everything?"
Sam bit back a biting response. "Yeah. Cas, I need you to swallow this pill. Do you need some water?" He nodded and Sam cracked open the bottle of water he brought.
"What are you giving him?" Dean asked.
"Nitropress. It'll dilate his blood vessels."
"But then won't the poison go throughout his whole body?"
"It already is. But if we get it out of the lungs, the rest will wear off within the next few hours. The only thing the poison is doing is making him human. It's the buildup in the lungs that's the problem." After Cas swallowed the medication, Sam took out a small bowl and a large needle in a package. "Cas, I need you to lie back against Dean, OK?" He nodded and reclined, though it made him cough more and choke a little. "Dean, you're gonna have to hold him down." Dean nodded and wrapped an arm tightly around Cas' waist.
"I don't understand. Why would Dean need to hold me down?"
Sam exhaled loudly. "Because this is going to hurt, Cas." He rubbed iodine on Cas' chest, and the man's eyebrows furrowed at the yellow color. "I'm sorry," Sam said before he plunged the needle into Cas' lung.
Dean had never heard someone scream like Cas did at that moment; not even the screams in Hell had been that bad. Maybe it was because Dean loved Cas, and that made it painful. But whatever the reason, he reflexively tightened his arm around Cas' waist.
Sam drew the blood out of Cas' lung and squirted it into the bowl. Needle after needle pierced the angel, who screamed and cried with every plunge. Dean had tears cascading down his face, and Sam was close to crying himself.
"De-e-an!" Cas cried, turning his face into the soft skin of Dean's neck.
"I'm here, Cas," Dean choked, letting his tears soak into Cas' hair. Finally, Sam drew the plunger back and no blood came; Dean sagged back in relief. "Oh, thank God," he groaned.
"That was only one lung, Dean," Sam replied.
Cas, who had relaxed along with Dean, suddenly tensed up and squirmed against the man behind him. "Sam, please," Dean begged.
Sam schooled his features as he prepared another needle. "I'm sorry," he repeated before stabbing Cas' other lung.
Cas screamed out again, his chest rising and falling rapidly, and Dean openly sobbed, unable to stand the sight of Cas writhing in pain. "Shh," he tried to soothe. "I'm here, Cas. I'm right here."
"Dean! Make it go away! Please!" Cas begged.
"Soon, baby," Dean promised, rocking Cas a little in between Sam's ministrations.
"Now!" Cas screamed, getting hysterical.
"Cas," Dean choked out before taking a deep, shuddering breath. "I love you," he said just as Sam stabbed again and drew back air. As soon as Sam removed the needle, Cas dropped off into sleep. "Cas?"
"He needs rest, Dean," Sam said. His voice was calm, but Dean saw his hands shake as he put down the needle. "He'll sleep off the rest of the poison and wake up in a few hours."
"And he'll be...an angel again? He'll be OK?" Dean asked as Sam carefully put bandages on Cas' chest.
"Yes. He'll be fine. Are you OK for me to go to my own room?"
Dean nodded, knowing Sam was more shaken by what he had to do than he let on. "Sam," he said as he brother neared the door.
"Yeah?"
"Thank you. I don't think I could have done it."
Sam nodded once. "Of course, Dean. Get some sleep," he said before closing the door behind him. Dean stroked Cas' hair before dropping off to sleep himself.
Cas woke up after six hours and grinned. He could feel his grace again. He looked up to see Dean blinking blearily, having been woken by Cas moving his head out from under his chin. "Dean, I'm OK. My grace is back."
Dean grinned and gave him a hard kiss. "I'm so sorry you had to go through that."
Cas nodded. "Thank you for being there for me."
"Of course. I love you."
"I love you too, Dean."
Dean grabbed Cas in a hug and closed his eyes. He was enjoying the moment when his stomach rumbled. "I'm hungry."
Cas laughed. "Burgers?" Dean nodded, and Cas mojoed burgers and fries for them. Dean didn't even mind, too tired to drive to a diner.
They were just digging in when Sam knocked and opened the door a crack. "Can I come in?"
"Come have a burger, Sammy," Dean said, watching Cas procure another order out of thin air.
Sam sighed. "Just this once." He frowned before taking a bite.
"Sam, I must thank you. You saved my life."
Sam blushed. "Of course, Cas. You're my friend. And Dean loves you beyond anything. Could you imagine what I'd have to deal with if you weren't around?" he said, trying to lighten the mood. Dean offered his brother a small smile. "Well, I'm off to bed," he concluded, having finished his burger. "Goodnight, guys."
"Night, Sammy."
"Goodnight, Sam."
Dean threw away their trash and stripped off his jeans, watching as Cas undressed as well. They slipped under the covers, and Dean cradled the back of Cas' head in his palm. Dean quickly fell asleep, and Cas pressed his nose to Dean's chest, settling in and watching calmly over Dean.