Notes:

For thewinchesterlifestyle.

Because of thewinchesterlifestyle on Tumblr I'm completely obsessed with this dogboy stuff...so blame her!

Dean watched as his dog sat on the couch whining in pain as his rut took him full force. Ever since he woke up this morning, he had been in this constantly hard and painful state..

Dean knew that it would happen someday. He'd had his dog ever since he was a kid but Cas hadn't seemed to exhibit any sexual behavior at all. Of course Cas would want to breed. It was in his nature and shame on his dad for never getting him fixed. But what was done was done and Cas was suffering now. Dean didn't know what to do. He couldn't just go knock on the neighbor lady's house and ask to let his dog fuck hers.

He supposed he'd have to get Cas fixed right away after this passed. It would be cruel to make Cas go through another rut alone. He hated seeing his dog in pain. He loved Cas and he wouldn't put him through any more suffering.

Dean moved over to the couch and sat next to the dog who was covered in sweat, the heat had spread all the way to his ears and the tips of his black hair were damp with sweat now. He took his damp cloth and started wiping Cas's forehead and the dog moaned, shifting over and cuddling up to Dean as the hunter wiped the sweat away.

"There, there, boy. It's okay. It'll be over soon." Cas whined, nuzzling into his neck.

"Dean. . ."

"Shh, it's okay. I'm here. I'm not going to leave you." He pulled the dog into his lap so that their torsos were facing each other. He blushed, realizing that was a bad idea when he felt Cas's hard cock jutting out through his sweats. It was jabbed against his stomach and Cas whined at the impact, thrusting his hips forward automatically, trying to get some friction. Dean tried to still the dog's hips but Cas was stronger than him. Cas was licking his neck now and making whining noises as he rutted his dick against Dean. Dean gasped, feeling Cas's teeth nip at his neck.

Cas was strong. . . He was in a rut. He wanted sex. He was dangerous.

He could. . . Help his dog a little, couldn't he? It was his fault he never had Cas fixed in the first place. It's not like anyone had to know about this.

Dean bit his lip and wrapped his hand around Cas's cock that was still covered in sweatpants. Cas yelled out in either pain or pleasure—Dean didn't know which.

"D-Dean. . ." Cas rutted firmly into his hand, hips moving to piston violently forward and back. A low growling sound was erupting from Castiel's throat and to Dean's horror, he found himself getting turned on by it. He squeezed Cas's dick harder, rubbing as the dog thrust into it.

"Does that feel good, boy?" Dean said, his voice a bit breathless. There was wetness forming at the top of the pants now and Dean couldn't resist pulling the pants down and letting Cas's dick spring free. He gasped at the size of it, so much more girth than his and so much longer. His balls were heavy between his legs so full and ready to breed. When he wrapped his hand around Cas's cock, it was red and burning with heat. Cas yelled out a gain, growling deeper as he started thrusting violently into Dean's hand.

"D-Dean. . . more. . ." Dean was panting now, his pants becoming too tight. It was wrong, touching your dogboy in the light of day. . . getting turned on by it, but Dean couldn't help it. Cas was gorgeous with his dark blue eyes and shaggy hair, slick with sweat. His lips were swollen pink from biting and Dean was startled at how hard it was to resist kissing him. He didn't know how Cas would react to that.

"What do you want, Cas?" Cas thrust hard back and forth into Dean's hand.

"B-Breed. Want to breed."

"You wanna breed, don't you Cas?" Dean bit his lip, his heart pumping with the adrenaline of what he was about to offer. "Do you wanna breed me, boy?"

"Dean. . . Breed Dean. . ."

"Yeah. I'll let you try to breed me. It won't work but I'll let you do what you want okay?"

"Dean!" Dean yelled out as his panting dog pushed him down on the couch, lifting up his hips and rutting his cock against his ass. Dean laughed at Cas's frustrated groans as he started pulling at his owner's tight jeans.

"You ain't getting anywhere like that." Cas started growling again. Dean chuckled. "Shh, now. I'll help you out. I told you I would. I'm going to go get something and then I'll be back." Cas started whining as Dean stood up, patting his head. Dean laughed. "I promise I'll be back soon." Dean leant down and kissed Cas softly on the lips before turning away with a blush and heading to the bathroom.

Dean quickly found his lube and went to work, slicking up his hole and stretching himself. He hadn't ever slept with a guy but he'd done enough research to know he needed to be stretched well before taking a dick up there. It was always easier to just sleep with women while he was on the road. The most he'd ever done with a guy was a mutual hand job and some making out. It was thrilling to think his first time anal was going to be with his fucking dog. He closed his eyes tightly against the burn of each stretch but he knew it would feel good soon. Cas was huge so he needed to take a little bit of time to do it properly lest he end up not being able to walk tomorrow. Bobby would ask questions.

Dean found his prostate and started rubbing himself hard again as he pressed on it. He bit back a moan and drew his finger back. Yeah that would work. . . God he wanted Cas to fuck him so badly. . . It was so dirty wanting his dog to fuck him, but the idea of it being so forbidden was the very thing turning him on even more. He couldn't find the living room faster and it wasn't until he was out there that he realized he was still in his t-shirt but was completely bare from the waist down. He was hard and it jutted out before him, bobbing in the cool air and Cas took one look at him and started whimpering, shifting on the cushion and rutting against nothing.

"Calm down, Cas." He bit his lip, letting the red skin pop out his mouth slowly as he spoke again. "You wanna breed me?"

"Dean. . . Breed Dean." Cas's voice was wrecked now, rough and low and it just sounded like sex in Dean's ears and he scrambled to the couch, remembering the documentary he'd seen about dogboys and girls and their breeding habits. He carefully positioned himself so that his back arched and his legs were spread wide, his arms over his head. He heard a low whine because Cas would instinctually recognize this as 'presenting' and Dean smirked.

"Breed me, Cas." Cas whimpered and Dean felt something hot and wet at his hole before there was nothing but a whole lot of pain as Cas tried to push himself in. Cas was a dogboy so he wouldn't realize that Dean didn't stretch the way doggirls did, but it was okay. The pain would pass. Dean bit onto the cushion as his body started trying to accommodate to Cas's size. He needed to do his best to relax or this wouldn't work.

Finally Cas was breached and on a mission to push himself in. It burned but it wasn't the worst pain Dean had ever experienced. He knew what he was in for when he started this. Suddenly Cas stopped and Dean looked back.

"W-What's wrong, Cas?" Castiel's face was strained, as though it was taking every ounce of his will not to fuck Dean as fast and hard as he could right then. His hands were digging into Dean's white hips and he'd probably have bruises later.

"Dean. . . hurt. . ." Dean blinked. Surely he must have misheard?

"What?"

"Dean. . . pain." Dean chuckled, his voice strained because fuck yeah, pain.

"Just a little, Cas. I'll be fine. You don't need to stop."

"Cas will wait. Dean hurts. . ." Dean bit his lip, feeling his stomach fill up with butterflies because his dog was so fucking sweet.

"Aw, you're so cute. Who's a good boy?" Cas whined and Dean bit his lip because Cas probably wouldn't be able to properly appreciate the praise when he was literally in pain with arousal. They waited a minute and Dean wiggled his hips. "Come on, I'm good now, Cas. Go ahead."

"Want to breed Dean. . ."

"Yeah, breed me, Cas. Breed me good." Dean braced himself as Cas wasted no time burying his dick to the root inside of Dean's ass. He moaned, never feeling so full before even with the few dildos (miniscule in comparison) he'd experimented with. "Oh God. . ."

Cas was growling now, rutting his dick hard and fast into Dean's tight hole. Dean could hear those powerful balls slapping against his as as he was fucked by his dog. It was so dirty and hot and he was moaning like a slut. Cas was muttering a litany of "Breed Dean full. . . Dean is a good bitch"

"Nnnn yeah breed me, Cas," Dean opened his mouth and moaned out loud, feeling Cas strike his prostate dead on and proceed to bump into it clumsily thereafter. "Oh yeah. . . fuck. Such a good dog. . . so big." Dean clamped down on that dick in his ass, causing Cas to howl and fuck into him faster and faster. "Does it feel good, Cas?"

"Good. . . So good, Dean. Dean is a good bitch."

"Yeah I'm your bitch, Cas. . ."

"Mate Dean. . ."

"Ah yeah. . . Fuck. Mate me Cas. . ."

"Full of my puppies."

"Yeah. . . " Not really. Since Dean was human and it wasn't possible.

"Fill you up. . ." Dean winced as he felt a pressure catch on his rim and suddenly he remembered that thing about dogboys.

"F-Fuck is that your knot?"

"Knot my bitch. . ." Cas pushed the pressure forward and Dean groaned in pain but he couldn't help but get excited at it at the same time. Suddenly it was swelling so big and he could feel it move up and against his prostate as Cas moved. Dean wrapped his hand around his dick and jerked it furiously, moaning against the couch cushion as he was knotted like a bitch in heat.

"Fuck!" Before he knew it, Cas was locked inside of him. The pressure dragged up and down his channel as Cas's thrusts got shorter until he as just grinding against his as at that point. Cas was so deep inside and was whimpering more now, bending over and licking at Dean's neck, nipping it. "Fuck yeah, Cas. . . breed me."

"M-Mate Dean. . . Good bitch tight around my knot. . . Ah!" Cas was coming. Dean could feel the heat in his ass. It was so wet inside his ass now but the come had nowhere to go with the knot blocking it from escaping. Dean felt his cock jerk in his hand and he came with a shout, clenching around his dog's knot and wrenching out another orgasm. Cas fucked shallowly into him, filling him up with his seed. Dean's cock spurt all over the couch, painting it white.

"Good, boy. . ." Dean twisted himself carefully so that he was on his back, pulling Cas on top of him.

"My mate."

"Yeah I'm your mate, Cas." Cas licked his face, licking into his lips and Dean sucked on his tongue, squeezing his ass around that still big knot. Cas whimpered, rutting and spurting more come inside his owner again.

"You'll be full of my puppies."

"I don't think it works like that, Cas. . ."

"You will be." Cas sounded so confident. Dean didn't have the heart to tell him it wasn't possible.

"Okay. Yeah I'll have your puppies. But you'll have to breed me a lot to make it work."

"Yes. Breed. A lot."

"Looks like a pregnancy, but I've never seen anything like this before. It was never possible for dogboys to actually breed humans." Dean felt lightheaded as he looked at the ultra sound picture. This couldn't be happening. It wasn't possible, even the doctor said! But the roundness of his belly and the morning sickness begged to differ.

"Dean is full of my puppies" Cas said proudly and the nurse smiled nervously at him, glaring at Dean because of course there was only one way that would even possibly happen.

He wondered if he was going to be arrested for letting his dog fuck him. . .