
Posted originally on the Archive_of_Our_Own at https://archiveofourown.org/
works/8450353.
  Rating:
      Explicit
  Archive Warning:
      Underage
  Category:
      M/M
  Fandom:
      Supernatural
  Relationship:
      Castiel/Dean_Winchester
  Character:
      Castiel, Dean_Winchester, Mary_Winchester
  Additional Tags:
      Alpha/Beta/Omega_Dynamics, Alpha_Castiel, Omega_Dean, Alpha_Castiel/Omega
      Dean_Winchester, First_Time, Mating_Cycles/In_Heat, Innocence, Knotting,
      Submission, Claiming
  Stats:
      Published: 2016-11-02 Words: 1533
****** Dean Was an Omega ******
by omegadeanlovesalphacas
Summary
     Innocent 13 year old Dean has only recently presented as an Omega,
     and doesn’t know why his neighbor suddenly smells so nice…
Notes
     Warning! This is an Alpha/omega kink prompt fill. Expect more porn
     than plot, and lots of power imbalance between Cas and Dean. Mind the
     warnings and kinks in the tags.
     Anonymous asked:
     A young Dean *as young as you can take it* having recently presented
     as an omega, suddenly really curious about his older alpha friend Cas
     *early to mid 20s*. Maybe he subconsciously begins trying to entice
     and 'woo' Cas into claiming him. *sly/flirty touches, innocently
     asking about the large bulge in Cas' pants, etc.*
See the end of the work for more notes
Being an omega really sucked. That was Dean’s conclusion, since apparently
waking up “smelling omega” on his 13th birthday meant that he wasn’t allowed to
leave the house alone anymore. He used to be able to ride his bike all over
town by himself, now his parents seemed determined to keep him under an armed
escort at all times. 
They had promised that after his first heat he could have a little more
freedom, once his cycle was predictable. They said they didn’t want him outside
by himself when his heat could hit any day.
Dean’s mom had tried to explain, said something about how Alphas have no
control when an omega is in heat. Then she’d given him a shoebox and said,
“you’ll know what to do with these when your heat hits.”
Dean had only looked in the box once before he shoved it as far under his bed
as he could reach. He didn’t even know what his mom expected him to do with
plastic dicks, he had a dick, why did he need a fake one?
“Fuck this,” Dean muttered. It only took him a minute to climb out the window
and find freedom. 
His bike was locked up in the garage, so Dean would have to move on foot. Which
meant there weren’t many options for him, since the arcade and the diner were
too far to walk.
That was when Dean saw Castiel doing yardwork a few houses down the street. 
Cas was Dean’s neighbor; a 24 year old Alpha who had just bought his first
house. He had a good job apparently, marketing or something. But he wasn’t like
most Alphas, he was super nice and would let Dean hang out, eat his food and
play video games. Dean wasn’t worried about Cas in the slightest. 
Dean ran down the road, grinning as he neared Castiel. “Hey, Cas!”
Cas looked up and smiled, “Hello Dean!”
As Dean approached he caught an interesting scent. It smelled amazing, Dean
wanted to get closer to it. When he realized it was coming from Cas he blinked
up at him in innocent confusion. “Are you wearing cologne or something?”
Castiel frowned. “No, I don’t wear-” He stopped, eyes going wide. “Oh. You’ve
presented, I can smell it.” He shifted a bit where he stood. “You can scent me
now, Dean.”
“Oh,” Dean said. “So that’s what an Alpha smells like? I could tell my parents
had a scent after I presented, but it didn’t smell as strong as yours.”
“Ah, yes.” Castiel looked a bit uncomfortable, and Dean didn’t understand why.
“Your parent’s scent will be familiar to you, but not as strong as an unrelated
Alpha.”
“Oh, okay.” Dean shifted a bit as he felt a bit of slick in his pants. That had
been happening more and more lately, and it was definitely up there on Dean’s
list of annoying omega things. “Can I use your bathroom?”
Castiel seemed to hesitate for a moment before he let Dean inside. 
===============================================================================
Dean was an omega. Dean was an omega.
Dean is 13 years old, stop it,Cas tried to tell himself.
Castiel shook his head as he followed Dean into the house. He was so completely
thrown. Last week Dean had just been a neighborhood kid, but today he was a
newly presented omega. A beautiful little omega who currently smelled faintly
of slick and probably an impending heat.
When Dean reappeared from the bathroom Cas tried to find a way out of his
predicament. 
“You know, Dean, it’s kinda late. Don’t your parents want you home?”
Dean shrugged. “They won’t miss me.” He moved towards Cas, trailing his hand
over Castiel’s couch and leaving his scent behind.
Dean approached Cas slowly, curiously, submissively avoiding eye contact. “You
seem different, now.” He stepped closer, now just a foot away. He ducked his
head and bared his neck, although Cas was pretty sure the boy didn’t even know
what he was doing. “Now that I’m an omega am I supposed to behave different
around you? My parents haven’t told me much.”
It took all of Castiel’s will power not to scent and bite the exposed neck in
front of him. He could feel the primal Alpha part of his brain steadily eroding
control over his logical, civilized mind. His cock was swelling, getting harder
by the moment.
“No, it’s fine Dean, you don’t have to behave any different,” Cas said, voice
straining.
Except the omega clearly was. He looked up at Cas. “Can I ask you something?”
He ducked his eyes again. “I presented kinda early, and we haven’t done sex-ed
yet.” He bit his lip. “How exactly does a male Alpha and a male omega have sex,
anyway? I mean, two dicks? I don’t get it…”
Cas frowned. “I don’t think that’s an appropriate…” 
“Why are your pants bulging out?” Dean suddenly asked. “I’ve heard Alphas are
extra big, is that why?” To Castiel’s shock the boy reached out and touched
him.
Castiel reached out and snatched Dean’s hand away from his hard cock. And that
was when he smelled it. Slick. Castiel could smell omega slick. Stronger than
before, and so very, very sweet.
===============================================================================
Dean was so confused. He just really needed to be closer to Cas. The Alpha was
suddenly the most interesting person Dean had ever met and he needed to figure
out why he smelled so good. 
But he needed to do that while also making himself smaller. Because he didn’t
know why, but he really needed to be small in front of Cas, and he really
needed to show the Alpha his neck. He needed Castiel to tell him what was going
on, to tell him what to do about it. 
Was this what they called submission?
Dean shifted as he felt the slick gush out of his ass again. He didn’t
understand why, it had never been this bad before. He could feel it quickly
soaking through his jeans.
When Castiel spoke his voice was rough. “Dean. You need to leave. Now.”
Dean finally looked up and made eye contact with Cas. His eyes were blown wide,
dark with something intense.
For some reason the look made Dean drop to his knees. “Alpha. What’s happening?
Please…”
“You’re… you’re going into heat,” Castiel managed. “You need to go home. Now.”
“But, I want to stay with you,” Dean said. And he did. He wanted Cas, wanted to
stay with Castiel forever. And he wanted, needed, something else. His ass was
starting to ache and burn, hot and wet with need. It was like an itch, it was a
need that Dean had to have filled. Yes, that was it, he needed to be filled.
“Please, Alpha. Please.”
Castiel suddenly grabbed Dean by the hair and yanked it back, forcing him to
make eye contact. “Do you even understand what you’re asking for?”
“Yes.” Dean knew. He didn’t know a lot about sex, but he knew that omegas
belonged to Alphas. He liked Cas, he could belong to Cas. He needed to belong
to Cas. “Wanna be your omega. Please, Alpha! Please claim me.”
Any control Castiel had was shattered, and he picked Dean up and shoved him
onto the couch on his belly. Dean could barely register what was happening as
Cas yanked down his jeans and shoved two fingers into his ass.
“Oh!” Dean gasped, jerking his hips in both pleasure and shock. “C-Cas, what
are-?” But he lost his words as the fingers pumped in and out of his ass,
quickly adding a third one. Then there was suddenly something much bigger
pressing against his hole.
Dean cried out as Castiel’s large cock was driven deep inside him. 
Castiel’s mouth pressed to Dean’s ear. “Now you know, little omega,” he
growled. His hips pulled out and then drove back in, setting up a fast,
claiming pace.
Dean squirmed under the Alpha’s weight, brain shut down from conflicting pain
and pleasure. This was nothing like what he expected, but he needed more. Even
though he didn’t even know what more was. 
He soon found out when only a few minutes later the Alpha’s cock started to
swell, growing bigger and bigger as it stretched and filled him. He felt he was
surely going to be split open, but it was also the most amazing thing he’d ever
felt. The giant knot pressed harder and harder on a bright spot of pleasure
inside Dean, until he finally came with a cry and a long moan.
Castiel grunted and slammed his knot into place in the omega’s channel. Too far
gone to stop himself, he leaned in and bit down hard on the back of Dean’s
neck, claiming him. He then collapsed on top of Dean, letting out a long groan
as his cock pulsed and steadily pumped his seed into the young omega’s ass.
Dean moaned and pushed back against the knot. Even after coming it felt so good
the way it filled him and stretched him.
Claimed him.
He looked back over his shoulder at Castiel. The Alpha looked at him with fond
exasperation. “Your parents are going to kill me.”
Dean just grinned.
End Notes
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