This is your one and only Destiel warning.

Dean and Castiel... will be getting involved with one another.

... Sexually.

Thought you ought to know.

Bursting in, Dean's heavy footsteps scuffed over the hardwood floor, the door slamming behind him. Dust curled in the bright golden sunlight streaming through the window where he walked. The day had been cool but still. No wind followed him. He threw his father's journal onto the bed and began to pace. Worry creased his fine features, and lay heady on his shoulders. His green canvas jacket seemed to weigh on him. As he moved about the room, his boots dragged. His usually bright eyes were clouded. They cast about the room with a twinge of nostalgia. He sank into a chair and slid back, gripping the arm rests with both hands, and anxiety loosened its grip on him.

This room was heavy with wear. Many people had come and gone from this room. They had gotten drunk, stewed for hours over crap TV, and fallen dead asleep in these beds. Kids had drifted off beside slumbering siblings, mounded in blankets; some had been looked over by lovers and guardians of all sorts. He had seen thousands of places just like this over the years. Thousands of rooms, filled with thousands of memories – many not his own. He couldn't even begin to describe his attachment to these cheap motels. They were like a piece of his childhood. He remembered the travel with his father – the long nights watching over Sam. The bowls of cereal, the pouting and parent faking, and days staring out dusty windows. Just waiting. Waiting for Dad to get back.
Dean leaned forward and put his face in his hands. Sam had gone out on a hunt by himself, not two hours ago, after they had butted heads again. Demons again. Crowley and his minions. Damn demons. 'No more deals!' He had shouted. Then Sam had taken his backpack and hiked off without looking back. But he'd be back. Of course he would.

"Dammit," Dean whispered, and got up abruptly, stalking to the table. There waiting for him was a few shot glasses and a bottle of whiskey. In his hands, the bottle was smooth and cold. The cork popped out easily. He poured himself a shot and sighed, swirling the rich liquid around before downing it. Sam was out there and back from perdition and he couldn't even keep him grounded long enough to make sure he was gonna be ok.
"Dean." Came a voice, and Dean jumped out of his skin. Turning, he saw Castiel standing in the center of the room, looking as if he'd just walked there all the way from Texas. He was all shadowed blue eyes and set jaw, his clothes mussed more than usual with dirt and dust, and blood all over his hands, as well as streaked on his face.
Confusion drew over Dean's face. He crossed the room in two steps and put aside his shot glass. "Cas? Jesus, what happened to you?"
Castiel glanced at Dean up and down, sighing. "Raphael's men. I think I'm getting to him." He looked around the room, eyebrows knitting. "Where is Sam?"
"Hunting," Dean replied gruffly. "He wanted to go off on his own for a while. Why?"
The awkward understanding that they had fought hung in the air a few seconds before Castiel gave him a look and glanced off again. "I see. No reason; I believe Sam knows how to fend for himself."
"Yeah. You and me both." Dean sighed. "You're still bleeding. How long does it take for you to heal again?"

Castiel looked at the mirror through the open bathroom door and squinted at himself, as if annoyed at the blood. "I'll probably be healed up by morning."
Walking into the bathroom, Dean reached for some washcloths and ran them under the tap, squeaking the handle as he turned it off again. He wrung them out. The excess water rained back into the worn white sink, trickling down the drain with distinct 'plips,' like creek water rushing over rocks. He turned and motioned to the Angel's wound. "Well, until then you should take care of that," he pointed out, walking back and approaching the Angel with his hand extended to clean the blood off his forehead. He drew back at first, and Dean gave him a look. "Come on, man. It's just water."
"Yes," Castiel replied shortly. "But it is still painful to the touch. It will heal on its own."
"Don't be a baby," Dean shot back, handing him two of the rags. "Your hands too, serial killer, before you get it on something and the maids report us." Hesitantly, Castiel took the rags, but he stood very still as Dean began to clean the slash on his forehead. No one had really done this for him before, he assumed. He'd probably just always wandered around until he was healed. The Angel blinked rapidly in discomfort at the cold on his aching forehead, though he did not move, staring fixedly at Dean's shirt collar to focus on not moving. With a trained touch Dean cleaned up the cut and bobbed his head. "There." Castiel looked up and was staring at him oddly, so with a devious smirk Dean pushed a smudge of dirt off the Angel's cheek with a clean corner of the cloth. Mildly startled, Castiel flinched and looked at Dean curiously. His reaction made Dean chuckle. He shook his head, "You can handle a war but simple stuff shocks you. Sometimes I forget you didn't grow up and do all this, you just popped into Jimmy there. Hands, Cas," he said as he turned and headed back into the bathroom. "If we only ruin one of these things someone's bound to get suspicious."
Going to touch his cheek to feel the cool there, Castiel thought better of it, seeing as his hands were still messy. "Not entirely unpleasant. But I still believe it unnecessary," Castiel muttered as he cleaned off his hands. "When I teleport, it would have just vanished." Red soaked the wash cloths.
With a shrug Dean poured two shots of whiskey, bottle clinking glass. "Well, you haven't gone anywhere yet, and if you ever get stuck as one of us you'll know how." He brought Castiel a glass as he finished cleaning off his hands. "Not to say I'm not glad to see you, but why did you decide to pop in, if you don't mind my asking?"
Clean fingers closed around the glass and Castiel nodded to Dean. "I came to make sure you boys were all right." He handed Dean the cloths and looked down at the drink. "When they come after me, they use more forces than when confronting the two of you, but I dislike the idea of you facing any Angels on your own. Even together - the two of you - they're a tough crowd to beat."
"You just said Sam would be fine, though?" Dean questioned as he tossed the soiled cloths on the floor of the bathroom and going to sit on the end of the bed. Sinking down and creating creases into the thin blue comforter, he leaned his elbow on his knees and sipped his drink, squinting at the quiet man. "So what's the big deal? We're invisible, right?"
Castiel's eyes flickered. He turned away and sipped the drink, walking to the window. "Raphael's Angels are unpredictable. I see now you are unhindered but he may send them soon. I don't wish to leave before they arrive, if they do arrive." The light slid away, sinking over the hoods of the cars in the parking lot, and the lampposts outside flickered to life. Their glow crept onto Castiel through the curtains and profiled him in dim white light; the point of his nose, the part of his lips. His eyes took on a pale glimmer. "You are indeed hidden specifically, as in your location, but he has… informants." The hair on the back of Dean's neck bristled. So Sam may still be in danger. He gripped his glass angrily and glared at it. And they'd separated. Again. Castiel looked over at him, the light spilling over his curious expression. "I am sure Sam doesn't wish to be bothered with my protection right now." He walked over to Dean. "But I do intend to remain here for the moment, just to be safe."

"A sleep over, Cas?" Dean laughed. "Really?"

"I do not sleep," came the irritated reply. "But yes. I believe it necessary, and for now I finally have time to spare. My plans are in a stage I need not govern."

"Is that supposed to be a good thing?"

Castiel finished the drink with one easy swallow. "Yes. Any more of this?"

"Plenty," Dean smirked, motioning to the table.