Disclaimer: I don't own SPN.

This was meant to be prompt 85 of Moments but it got a bit out of hand and I might turn it into a full-length fic. This whole 'fic out of a Moments prompt' has been happening a lot…

This is set before 9x04, so Charlie's not in Oz or anything. And yes, Zeke was quite passive and non-interfering in this but hey, he didn't interfere in 'Dog Dean Afternoon' except for a brief moment so why now?

How could he have been so stupid? Dean should have remembered that Cas was only human! Why didn't he stop and think for one minute that this might have happened before forgetting about the ex-angel and leaving him out in the cold after his fall? And why did he have to be such a sucker and drop everything and come running as soon as Cas had called in distress and begged for help?

"Don't you want to play with me anymore, Dean?" Cas sang innocently as he advanced on Dean, who was pinned to the wall of the motel. Only it wasn't Cas anymore; the pitch black eyes shining out of his face, replacing the usual soft blue, very harshly reminded Dean of that. "I thought you loved me!"

"Get out of Cas, you son of a bitch!" Dean snarled, thrashing against his invisible bonds. The demon just chuckled softly.

"I've never possessed an angel before," he said, pausing in front of Dean. "Except he's not an angel anymore, is he? Poor baby Castiel lost his wings and it's all your fault."

It physically hurt Dean to glare – even though it wasn't Cas, it was still his body and Dean couldn't imagine ever looking at Cas in this way. He tore his eyes away from Cas to glance at the others, to see if he was getting back-up any time soon, but it looked unlikely. Sam was slumped in a corner, barely conscious and Charlie was conscious but trying not to cry through the bloody wound in her gut. It was shallow and wouldn't kill her but Dean still felt rage pool in him at the sight.

"I just can't believe how easy this all was!" the demon continued, his eyes now back to blue. Dean felt like he had been punched in the stomach at the pure hatred shining out of them. "Even Ginger Spice over there was protected! But no, you never even thought to protect your pet angel, did you?" The demon clucked his tongue. "This is what happens when you don't use protection, Winchester. You could catch something…nasty."

"Go to Hell," Dean snarled. How dare he talk about Cas like that? And it wasn't like he'd done anything to Cas! Because he definitely didn't feel that way about him!

"Been there, done that," the demon said dismissively. "Then again, so have you, am I right?"

He sighed and ran a finger down Dean's cheek. Dean shuddered in repulsion.

"There's so much crap in here it's not funny," the demon muttered. "I swear, your angel has a lot of issues with you. But you know what? I feel for him. I mean, it's your fault he lost his grace. It's your fault for not thinking of protecting him against the likes of me. And everything crap that's happened since he pulled you out of Hell? Well, that's your fault, isn't it? You're the one who made me rebel and throw away everything and how do you repay me? By getting me in the crap time after time after time!"

The demon was shouting by now, slipping into referring to Cas in the first person. Dean, meanwhile, was struggling not to show just how each word was the equivalent of a punch to the gut. Was this really what Cas thought? Had he really been bottling all of this up? And of course it was all right. It was his fault for everything that had happened to Cas! He was toxic! But why had Cas stuck around, then? Pity? Did he feel bad for Dean? Or was this an elaborate form of revenge? Was he drawing Dean so far in, being his best friend, making him fall helplessly in love with the ex-angel, before taking off and leaving Dean to slowly curl up and die? Did Cas even like him back in that way? And why was Dean acting like a teenage girl right now?

"And you know it's all true," the demon said, poking Dean in the chest. "You know it, don't you? That's why you're not fighting me! You know that I'm just telling you what Castiel really thinks!"

"Dean…" Charlie whimpered. "Ignore…him…"

The demon lazily flicked his hand and Charlie doubled over, crying out in pain.

"Don't touch her!" Dean bellowed, struggling with renewed vigour. "Just leave them all alone! Hurt me! Hell, take me! You can have me! I'll cut my symbol and you can have me if you just leave Cas alone!"

The demon actually seemed to be considering it.

"On the one hand, blowing smoke up your angel's ass hurts you a hell of a lot more than pretty much anything else, since your brother's got protection," he mused. "But on the other hand…" He traced a circle on Dean's shirt over his tattoo. "Who else could claim to have possessed the great Dean Winchester when even Michael himself couldn't?"

"Yeah," Dean agreed, his heart hammering. Was he really doing this! Being possessed was one of his greatest fears! "You're right. Not even the archangel Michael could use me as a condom. But you can! I'll let you inside me so long as you let Cas go!"

The demon whistled.

"Man," he said. "Your angel's got you by the balls, don't he? Alright, you got yourself a deal."

The demon stooped down to pick up a knife. Dean staggered when the force holding him to the wall disappeared.

"Go on, then." The demon held the knife out to Dean. "Cut it."

Dean briefly contemplated stabbing the demon before immediately throwing that thought away. It would do nothing but irritate the demon, not to mention kill Cas in the process, and that was something that Dean was trying to avoid.

'Although he'll probably kill everyone anyway once he's in you,' a small voice said. Dean paused in the middle of pulling the neckline of his shirt down.

"If I do this," he said, "I want you to swear that you won't touch them. Sam, Cas, Charlie – you'll let them go."

"Of course!" the demon said smoothly. Dean didn't trust him one bit but what could he do? He couldn't let that monster stay inside Cas for a minute longer! That thought made him force the knife to his tattoo and flick downwards, creating an oozing red streak and breaking the protection. Dean thought he might have imagined it but he immediately felt naked and vulnerable.

"Good," the demon purred. He grabbed Dean's face and pulled him in for a kiss that immediately made Dean gag in revulsion. It was Cas' mouth but it was not Cas – not only was it completely different from all of Dean's fantasies but there was an acrid taste of fire and sulfur in his mouth that made Dean want to hurl. And, as the taste became more and more pronounced, Dean realised that the demon was sliding out of Cas and into him.

'Breathe, Dean!' he thought as something scorching hot slid down his throat, searing it as it went. 'You'd do this for Sam! Do this for Cas!'

Dean's heart was hammering. He could feel himself growing more and more detached from his body, shoved into some small part of his mind, no longer able to control any part of his body…

'Wait! No! Get out of me!' he yelled mentally. But it was too late. He felt the evil black presence settle in his mind and heard laughter resonate all throughout him. Still able to see through his eyes, he watched helplessly as Cas collapsed but no matter how hard he tried, he couldn't bend down and help him up or check on him.

"Dean?" Cas murmured, struggling to sit up. Dean felt his body kneel down, gripping Cas almost tenderly. "Dean? What happened?"

Dean felt his eyes begin to sting and, by the way Cas recoiled in horror, knew that they must have been black.

"Dean's not here right now." Dean was alarmed to hear how low and menacing his voice grew. "Too busy being self-sacrificing and letting his angel lead him around by the balls."

The demon threw Cas into the wall. Cas let out a pained cry as his head slammed against the bricks and he didn't even fight back when the demon crossed over and hauled him up by the shirt.

'Hey, let him go!' Dean hollered, struggling against the bonds in his mind. 'You promised, you son of a bitch!'

'What am I, a crossroads demon?' the demon scoffed. 'Find one of those red-eyed bitches if you want a binding deal.'

Hefting the knife, the demon stabbed it into Cas' shoulder. Cas cried out and Dean could tell that he was struggling to hold back tears. The sight of his angel in pain made him fight even harder but to no avail.

"You're a worthless piece of crap, you know that?" The demon punched Cas across the face. "Seriously. First you were weak enough to let me slide down your gullet and then you were selfish enough to let your boyfriend take me up the ass?"

'SHUT UP!' Dean raged.

"I'm – I'm sorry, Dean," Cas choked out.

"Sorry's not good enough!" With every punch and blow he landed on Cas, Dean felt sicker and sicker but no matter how hard he fought, he just couldn't overpower the demon! "After everything I've done for you – all that loyalty I've shown you – you repay me by betraying me and leaving me again and again? Crowley – Leviathans – Meg – Naomi – Metatron –"

With every word, the demon slapped Cas across the face. Cas spat out blood, his eyes glistening, his jaw trembling.

"You're nothing but a liar and a traitor and I don't know why I stick around!" the demon bellowed. He paused and Dean could feel him sifting through his thoughts. "Well, I'm sure the sex would be great if I had the courage to pluck up the balls and tell you just how hopelessly in love I am with you. But that's about it, really. You're nothing but a broken shadow of an angel who's only really good for a fuck and a screw-around every now and then. I mean, look at April!"

"Dean…" Cas spluttered through the blood in his mouth. "Please…"

"And now look," the demon said scathingly. "You're just so pathetic that you're not even going to fight back. You know you deserve this, don't you? You deserve everything I do to you and it'll never even begin to make up for everything you've done."

He kicked Cas in the side. Dean was sickened when he felt bone crunch under his foot and he tried even harder to wrestle back control but he simply couldn't.

"I should put you out of your misery," the demon concluded, stooping down to slide the angel blade that Cas had somehow acquired out of his jacket. He grabbed the front of Cas' shirt and hauled the ex-angel to his knees. Cas scrabbled for Dean's wrist, clutching tightly with bloody fingers.

"Dean…" Cas wheezed, holding on as though Dean was a lifeline. Dean fought furiously not to do this but the demon was too powerful.

'Stop it!' he howled. 'Leave Cas alone! Don't kill him! You promised, goddammit, you promised!'

"Please, Dean…" Cas pleaded. "I need you, Dean…I-I love you…I love you, Dean…"

A sudden rush of heat surged through Dean's body. To his utter surprise, he felt himself thrust back into the driver's seat and he dropped the angel blade and staggered at suddenly having control over his limbs again. He could feel the demon still inside him, raging and fighting for control, but he forced the evil son of a bitch deep down.

"Cas!" Dean knelt down and cupped Cas' face. "Talk to me, buddy! You okay?"

Cas nodded weakly, still holding on to Dean's wrist. With every passing second, he could feel the demon regaining more and more control and when his eyes landed on the gleaming angel blade, he knew what he had to do.

"Dean?" Cas croaked as Dean picked up the blade. "What – what are you doing?"

"Ending this son of a bitch while I have the chance," Dean said firmly. He raised the blade, looking at Cas' eyes, wanting them to be the last thing he ever saw even if they were filled with horror. "Sorry, Cas. Tell Sammy he's a bitch and Charlie that she's an annoying geek."

Just as he was about to thrust the blade into his chest, he felt the demon roar and surge back up. Dean had enough time to cry, "No!" before the demon was back in control, smiling widely down at Cas.

"Dean's gonna pay for that one," the demon panted, toying with the blade. "Oh, he's gonna pay good…"

But suddenly, Dean heard a feeble voice nearby and his body whirled around. Despite being in very obvious pain, Charlie had started to recite an exorcism and Dean felt his body lock up as the power gripped him tight and began to force the demon out of every cell in his body.

"Cut that out!" the demon raged. Charlie ignored him, so he strode over to her, ignoring the oppressive force on him. He kicked Charlie sharply in the side, making her scream, but then Dean nearly cried in relief when Sam's raspy voice took over. The demon couldn't take care of two of them at the same time with the force of the exorcism weighing heavier and heavier on him and Dean felt him reach a sudden decision. The next minute, his head whipped back and he let out a hoarse yell as the demon forced its way out of his body through his mouth, clearly hell-bent on not going back to Hell. The moment the demon was gone, Dean dropped to the ground and tried not to slip into unconsciousness.

"Dean?" he heard Sam say. "Dean!"

"S'mmy," Dean mumbled, flexing his fingers and toes. God, it felt good to have control back again! He was never doing that again! But at least it had gotten that son of a bitch out of Cas…

Cas! Dean forced himself to his feet and staggered over to the bloody, broken ex-angel, who was staring up at him with pained blue eyes.

"Cas…" he forced out. "I'm sorry…I'm so sorry, Cas…"

"Not –" Cas hacked up blood. "It wasn't your fault, Dean. You came back…just as I did…in the crypt…"

Right, because Dean really needed a reminder of that. Forcing himself not to think about that, he gently cradled Cas and held him close.

"Dean?" Cas murmured. "I think – I think –" He coughed, staining his lips red with more blood. "I think I'm dying…"

"No!" Dean snapped. "No! You're not allowed to say that Cas! Don't you dare die on me! Not again!"

To his horror, Cas' head lolled. He wasn't dead but deep down, Dean knew that he wasn't far from it.

"Dammit!" he shouted. "Zeke! Heal him, damn you!"

The air seemed to shift and then Ezekiel was crouching down beside him.

"You realise that this will weaken me?" he said seriously. "I will have to spend even longer in your brother."

"You brought him back to life! Just heal him!" Dean snapped.

"As you wish." Ezekiel's hands began to glow and he laid them gently on Cas' torso. Dean grinned shakily in relief when the wounds began to close up and knit together and Cas' breathing seemed to strengthen. Ezekiel remained in that position for another moment before staggering back, his eyes flashing blue.

"W-What?" Sam blinked. "How did I – I was just over there…"

"You probably blacked out," Dean said quickly. He met Charlie's wide eyes and shook his head, sending a clear signal not to tell him everything. Though she clearly didn't agree, she nodded nevertheless and let Sam kneel over her and patch her up.

"Dean?" Cas murmured. Dean let out a small laugh when Cas' wide blue eyes fixed on him. "What happened, Dean? I was dying and –"

"I'll explain it all later, Cas," he promised, trying to ignore the way his stomach did flip-flops and how he felt the insatiable urge to just lean down those few extra inches and press his lips to the ex-angel's. Instead, he wrapped his arms around Cas and helped him to his feet, feeling a delicious thrill when Cas leaned against him and hugged him back (wait, no, that was definitely not a hug! Bad Dean!).

"I can walk, Dean," Cas said as Dean helped him over to Charlie and Sam.

"Don't care. I nearly killed you. I'm not letting you go."

Was it his imagination or did Cas lean into him a bit more? No, he was dreaming. Cas didn't feel that way! Not after all the crap he'd said! How could he hold that much shit about Dean and still like him?

But he'd said he'd loved him. He'd quite clearly told Dean that he'd loved him! Was that just a ploy to avoid getting killed? Was he just desperate and clutching at straws, willing to say anything to avoid getting stabbed? Dean knew that his feelings for Cas were genuine but did Cas feel the same way?

Dammit, he didn't know what to think anymore!