Sheith AU Where when Alpha's hit a certain age, They HAVE to have...
Vel @ Miquella Defender@blackpalaladin
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Nov 02, 2025
~12 min read
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1
Sheith AU Where when Alpha's hit a certain age, They HAVE to have an omega lock around their knot during rut in order to get through it safely.
The only problem is Shiro’s fiancée is human. Meaning he needs a Lock agency to get through his future ruts.
The only problem is Shiro’s fiancée is human. Meaning he needs a Lock agency to get through his future ruts.
2
Which is why six months before his wedding - he and his fiancée have to sit down with an agent to sign a million pieces of paper.
'And this - guaranteed?' Shiro’s fiancée stares down at the final sheet, 'There’s no chance of a bond forming?'
'And this - guaranteed?' Shiro’s fiancée stares down at the final sheet, 'There’s no chance of a bond forming?'
3
The agent smiles sunnily, and it makes Shiro’s baser instincts flinch, 'Bond inhibitors are standard with each omega. No scents are exchanged. The omega can't see or hear. This is simply a way to ensure the lasting health of your alpha.'
4
His fiancée nods with an impressed expression.
Shiro feels like he's going to throw up, 'This seems - not in the omega’s favor.'
'It's not for them, Takashi.' His fiancée says.
'Every omega consents to be here, Mr. Shirogane.' The agent assures.
Shiro feels like he's going to throw up, 'This seems - not in the omega’s favor.'
'It's not for them, Takashi.' His fiancée says.
'Every omega consents to be here, Mr. Shirogane.' The agent assures.
5
Shiro frowns down at the sheet, 'Bond inhibitors-.'
'Do you WANT an omega?' His fiancée turns a scathing look at him, 'They know inhibitors stop working after prolonged contact. It clearly states that they never give an alpha the same omega.'
Shiro hates every part of this.
'Do you WANT an omega?' His fiancée turns a scathing look at him, 'They know inhibitors stop working after prolonged contact. It clearly states that they never give an alpha the same omega.'
Shiro hates every part of this.
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'Instant bonds are also incredibly rare these days.' The lady smiles, 'Which is what makes this service so handy for relationships outside of the designation community.' She shuffles her papers, 'You have 6 month cycles?'
Shiro nods.
'Alright. We have a few omegas that match.'
Shiro nods.
'Alright. We have a few omegas that match.'
7
Shiro curls his hands into fists against his thighs, 'I have a cycle in two weeks. And one a week before our wedding.'
She taps her pen against a calendar, 'We can certainly accommodate you. Would you like to select a body type close to your fiancée?' She motions to his fiancée.
She taps her pen against a calendar, 'We can certainly accommodate you. Would you like to select a body type close to your fiancée?' She motions to his fiancée.
8
'Not necessary.' His fiancée grins, 'I keep him plenty satisfied and I don't think he'll have an issue thinking of me.'
Her laugh is tinkling and bright, 'Confidence is key to human/designation relationships. Give me ten minutes and I'll get you in the calendar.'
Her laugh is tinkling and bright, 'Confidence is key to human/designation relationships. Give me ten minutes and I'll get you in the calendar.'
9
She rises from the chair across from them and slips out of the room.
'We knew this would happen.' His fiancée says, 'It's just like a doctors visit.' He pats Shiro’s hand.
'We knew this would happen.' His fiancée says, 'It's just like a doctors visit.' He pats Shiro’s hand.
10
Except it's nothing like that.
It's sex outside of his committed relationship with a stranger whose senses have been all but eradicated.
'It doesn't seem ethical.'
'It's what you need. Well, that is until they can come up with a way to suppress ruts and heats completely.'
It's sex outside of his committed relationship with a stranger whose senses have been all but eradicated.
'It doesn't seem ethical.'
'It's what you need. Well, that is until they can come up with a way to suppress ruts and heats completely.'
11
Something about that comment rings a bell in Shiro’s head but he doesn’t get time to follow up because the agent returns with her irritating smile and a confirmation appointment for the first day of Shiro’s upcoming rut.
He is not ready. Not even a little.
He is not ready. Not even a little.
12
His fiancée wants sex before Shiro goes. But he only seems irritable and mumbling afterward because despite Shiro being horny as all get out - the chemical connection isn't there.
Shiro likes his fiancée. They have similar jobs and goals and familes.
They're perfect on paper.
Shiro likes his fiancée. They have similar jobs and goals and familes.
They're perfect on paper.
13
The marriage wasn't so much Shiro’s idea as it was his father's - who said that 3 years dating with no solid commitment was rude.
Shiro’s grandfather told him to wait as long as he needed.
But Shiro proposed anyway.
Perfect on paper. For family.
Not so much for Shiro.
Shiro’s grandfather told him to wait as long as he needed.
But Shiro proposed anyway.
Perfect on paper. For family.
Not so much for Shiro.
14
He arrives at his appointment early and nervous. The waiting room is horrifyingly clinical and he's not the only alpha in the room. When his name is called he almost doesn’t respond.
Who cares if he gets sick after his rut? Who cares if his lifespan shrinks a bit?
Who cares if he gets sick after his rut? Who cares if his lifespan shrinks a bit?
15
But he stands and he follows the short attendant through the pale blue hallways to a small room.
It looks like a normal hotel room. With a queen sized bed, a mini fridge with a clear front full of bottled water.
It's barren and cold. Shiro swallows thickly.
It looks like a normal hotel room. With a queen sized bed, a mini fridge with a clear front full of bottled water.
It's barren and cold. Shiro swallows thickly.
16
'First time?' The attendant asks, 'Don't be nervous. There are no cameras. But still strict rules. Do not remove the blindfold. Do not bite. No marks of any kind. The omega has multiple places in this room to call for help.'
Shiro relaxes, 'Good.'
Shiro relaxes, 'Good.'
17
The attendant gives him a curious look, 'Were you afraid to hurt them?'
'No.' Shiro shakes his head, 'I'm just glad there are failsafes for this. I don't like how impersonal it is.'
The attendant hums, 'Well, it's only used for unmated alphas and alphas in human relationships.'
'No.' Shiro shakes his head, 'I'm just glad there are failsafes for this. I don't like how impersonal it is.'
The attendant hums, 'Well, it's only used for unmated alphas and alphas in human relationships.'
18
'It's too transactional.' Shiro murmurs.
'But it’s a hefty transaction.' The attendant says, 'The omegas have full disclosure before accepting an alpha. They get a final say. Their comfort is always taken into consideration.'
'Thank you. Am I allowed to know his name?'
'But it’s a hefty transaction.' The attendant says, 'The omegas have full disclosure before accepting an alpha. They get a final say. Their comfort is always taken into consideration.'
'Thank you. Am I allowed to know his name?'
19
The attendant shakes his head, 'No sir. I'm sorry.'
'That’s okay.'
'Get settled and I'll send him to you in about half an hour.'
The attendant shuts and locks the door behind him.
The sound echoes in the near empty room.
'That’s okay.'
'Get settled and I'll send him to you in about half an hour.'
The attendant shuts and locks the door behind him.
The sound echoes in the near empty room.
20
Shiro takes in a slow breath and sets his duffle bag of clothes on the table near the window. The curtains are blackout and dark red like the sheets on the bed.
He can't tell if he's horny or nauseous.
The sex from the early morning left him unsatisfied and frustrated.
He can't tell if he's horny or nauseous.
The sex from the early morning left him unsatisfied and frustrated.
21
He doesn't realize he's been staring hard at the bed in the center of the room until a knock at the door startles him.
He glances up after the door squeaks open and clicks shut softly -
Revealing a breathtakingly lovely young man in a red robe.
He glances up after the door squeaks open and clicks shut softly -
Revealing a breathtakingly lovely young man in a red robe.
22
His hair is long and dark, braided neatly over his shoulder. The angles of his face are sharp and delicate, and Shiro’s inner Alpha snarls at not being able to see the eyes hidden behind a red blindfold.
He's every fantasy of the perfect man Shiro dreamed up as a young alpha.
He's every fantasy of the perfect man Shiro dreamed up as a young alpha.
23
Back when he was young and imagined having a mate to share scents and sensations and a connection unlike any other.
Before the real world told him that fairytale bonds were only that - tales.
Before the real world told him that fairytale bonds were only that - tales.
24
'Whenever you're ready.' The voice is low and smokey. Like a banked fire on a chilly night.
It shivers down Shiro’s spine.
He doesn't know what to do. How to even begin.
He hasn't had sex with anyone but his fiancée in three years.
It shivers down Shiro’s spine.
He doesn't know what to do. How to even begin.
He hasn't had sex with anyone but his fiancée in three years.
25
He walks cautiously across the room. Every instinct trying to sniff for threat - but only the sanitized cotton smell of the room remains.
He presses two fingers against the inside of the omegas wrist.
The omega doesn't even startle. Just rolls his wrist up.
He presses two fingers against the inside of the omegas wrist.
The omega doesn't even startle. Just rolls his wrist up.
26
'You can't hear me.' Shiro murmurs, bringing that delicate wrist to his lips, 'But I promise to treat you right.'
The omega tilts his head and Shiro sees gooseflesh rise across the skin of his arm.
He smiles against sensitive skin and wishes he could scent him.
The omega tilts his head and Shiro sees gooseflesh rise across the skin of his arm.
He smiles against sensitive skin and wishes he could scent him.
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But that's exactly why the bond inhibitors are in place.
Shiro presses another kiss against the wrist and tugs the omega gently over to the bed.
He maneuvers the omega to sit on the bed.
And doesn't know what the hell to do next.
Shiro presses another kiss against the wrist and tugs the omega gently over to the bed.
He maneuvers the omega to sit on the bed.
And doesn't know what the hell to do next.
28
The omega makes the decision for him.
The robe slips from his shoulders into the curve of his elbows as he leans back on them. His knees part beneath the fabric until it slips down into the dip of his hips.
Shiro's heart does something funny at the display. His fingers twitch.
The robe slips from his shoulders into the curve of his elbows as he leans back on them. His knees part beneath the fabric until it slips down into the dip of his hips.
Shiro's heart does something funny at the display. His fingers twitch.
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His mouth waters as the omegas tiny cock comes into view, soft and pink between his legs.
Before he can stop himself - he's following the enticing sight onto the bed. His hands pressing against smooth inner thighs.
The omegas soft sigh is music.
Before he can stop himself - he's following the enticing sight onto the bed. His hands pressing against smooth inner thighs.
The omegas soft sigh is music.
30
Shiro ignores the throb of his own arousal and the growling voice inside telling him to sink inside. Teeth. Fingers. Cock.
He noses against the omegas stomach, pushing at the robe until the soft skin is exposed.
He noses against the omegas stomach, pushing at the robe until the soft skin is exposed.
31
He mouths a kiss from belly to cock and takes the entire length into his mouth.
The omega gasps, thighs tensing under Shiro’s hands.
Fingers sink into Shiro’s hair, 'Wait - you don't - I'm already ready -.'
Shiro growls around him.
The omega gasps, thighs tensing under Shiro’s hands.
Fingers sink into Shiro’s hair, 'Wait - you don't - I'm already ready -.'
Shiro growls around him.
32
The omegas moan is warbly and uncertain. The fingers in Shiro’s hair tug and curl, the cock in his mouth fills and leaks again his tounge.
Shiro shudders with pleasure.
He suckles until the omega is a begging mess under him.
Shiro shudders with pleasure.
He suckles until the omega is a begging mess under him.
33
His hands make their way down to spread the omegas ass. Fingers finding him slick and sticky.
Shiro releases his cock and drags his tounge through tasteless slick.
His growl must sound distressed because the omega strokes his neck.
'You won't care once you're inside me.'
Shiro releases his cock and drags his tounge through tasteless slick.
His growl must sound distressed because the omega strokes his neck.
'You won't care once you're inside me.'
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And that's the best idea anyone has ever had ever.
Shiro knows immediately that his rut is in full swing.
He drags his slick-sticky lips over the flushed red of the omegas cock and up his belly to a nipple. Where he sucks and nibbles until the desperate pleas become unbearable.
Shiro knows immediately that his rut is in full swing.
He drags his slick-sticky lips over the flushed red of the omegas cock and up his belly to a nipple. Where he sucks and nibbles until the desperate pleas become unbearable.
35
The tip of his throbbing cock finds the wet heat of a willing hole and Shiro doesn't like that he can't ask.
Can't look into the omegas eyes and see the willingness to be streched on a strangers knot.
Can't look into the omegas eyes and see the willingness to be streched on a strangers knot.
36
Cool fingers find the base of his neck, thumb pressing against Shiro’s jaw.
He stares down at the beautiful omega. Skin flushed pink against blood red sheets beneath them.
'Come on, Alpha.' A whispered taunt and the tick of a smirk at the corner of swollen lips, 'Fuck me.'
He stares down at the beautiful omega. Skin flushed pink against blood red sheets beneath them.
'Come on, Alpha.' A whispered taunt and the tick of a smirk at the corner of swollen lips, 'Fuck me.'
37
Shiro grins at the confidence in the omegas voice. And watches those smirking lips part in a gasping O as he sinks to the hilt in hot, wet heat.
Strong fingers curl around Shiro’s biceps, his voice a moan, 'Oh, you're huge.'
Shiro’s body vibrates with a laugh.
The omega grins.
Strong fingers curl around Shiro’s biceps, his voice a moan, 'Oh, you're huge.'
Shiro’s body vibrates with a laugh.
The omega grins.
38
Shiro’s heart squeezes once, but the overwhelming heat of his rut takes over.
He pulls out, the drag of it smooth and sweet.
Then shoves back in, snarling as the omegas back bows and his tiny cock oozes into the dip of his belly.
He pulls out, the drag of it smooth and sweet.
Then shoves back in, snarling as the omegas back bows and his tiny cock oozes into the dip of his belly.
39
From there, it's a marathon of moans and sobs.
It's also the first time Shiro’s ever been able to think straight during a rut.
He's careful, but the omega begs for harder. More. His nails dragging down Shiro’s back.
It's also the first time Shiro’s ever been able to think straight during a rut.
He's careful, but the omega begs for harder. More. His nails dragging down Shiro’s back.
40
He feels the tight tingle of his knot at the base of his cock far too quickly for his liking. But the tight heat of the omega is just what he needs.
'Give it - give -.' The omega turns his head on the bed, mouth finding Shiro’s inner wrist.
'Give it - give -.' The omega turns his head on the bed, mouth finding Shiro’s inner wrist.
41
Shiro snarls and slams his knot past the tight ring of muscle.
The omega screams, lips parting against Shiro’s skin. Cum pools onto his trembling stomach.
And Shiro follows with a soul deep moan.
His head spinning and the scent of baked cinnamon soothing the heat inside him.
The omega screams, lips parting against Shiro’s skin. Cum pools onto his trembling stomach.
And Shiro follows with a soul deep moan.
His head spinning and the scent of baked cinnamon soothing the heat inside him.
42
Every muscle in his body relaxes as fragrant warmth settles around him like the best security blanket.
But he feels the omega tense under him. Feels soft lips tremble against his wrist.
A tortured whine and fingers curling around his forearm as sharp teeth sink into his skin.
But he feels the omega tense under him. Feels soft lips tremble against his wrist.
A tortured whine and fingers curling around his forearm as sharp teeth sink into his skin.
43
They don't break flesh but the sensation sends a feral heat across Shiro’s skin and he feels a pleased growl rumble from his chest.
The lock around his knot clenches and slick soaks around it.
And the scent of baked cinnamon sharpens.
The scent of -
The SCENT -
The lock around his knot clenches and slick soaks around it.
And the scent of baked cinnamon sharpens.
The scent of -
The SCENT -
44
'Fuck.' The omega sucks at the bite he left on Shiro’s wrist. His hole squeezed Shiro’s knot and sheer, overwhelming pleasure hijacks the terror creeping into Shiro’s brain.
He shoves his cock deeper and the omega keens, rocking down.
He shoves his cock deeper and the omega keens, rocking down.
45
His hands slide up Shiro’s arm to his shoulder, where he tugs and pulls until Shiro can only fall forward into a warm embrace.
His nose finds the curve of the omegas neck and that warm, homey scent is so thick he can taste it on his tongue.
His nose finds the curve of the omegas neck and that warm, homey scent is so thick he can taste it on his tongue.
46
He has no doubt that if he tasted the omegas slick now - it would taste like fresh baked cookies. Like all the warm things Shiro made standing on the stool in his grandfathers kitchen as a kid.
He swallows and burries his face in the omegas throat.
'I'm sorry.' He whispers.
He swallows and burries his face in the omegas throat.
'I'm sorry.' He whispers.
47
The omega can't hear him - but he nuzzles Shiro temple, 'Keep going. Please.' Warm, strong arms curl around Shiro’s back, 'Please?'
Every instinct Shiro has tells him to do what omega days.
Please the omega.
Satisfy the mate.
Every instinct Shiro has tells him to do what omega days.
Please the omega.
Satisfy the mate.
48
Shiro is a mess of contradiction for the next two days.
He alternates between worshiping the omegas body and filling him to the brim with cum. To standing in the shower alone wondering what the hell he's supposed to do next.
He alternates between worshiping the omegas body and filling him to the brim with cum. To standing in the shower alone wondering what the hell he's supposed to do next.
49
Then he hears the omega whine when he's gone for too long and every flash of guilt swirls down the drain.
By the end of the third day - Shiro is exhausted.
And satisfied in a way he's never been before.
By the end of the third day - Shiro is exhausted.
And satisfied in a way he's never been before.
50
'What do I do?' Shiro asks aloud, even though he knows the omega can't hear him.
The omega pulls his robs tight around his body. He's showered and that fresh cinnamon is now smothered by the shower gel.
Shiro HATES it.
The omega pulls his robs tight around his body. He's showered and that fresh cinnamon is now smothered by the shower gel.
Shiro HATES it.
51
'Act normal.' The omega says, 'Go home to your partner. When they give you the survey - you can be honest. The inhibitor was compromised.'
Shiro wraps a hand around the omegas wrist and brings his fingers to his lips, 'Will you lose your job?'
The omega swallows, 'Yes.'
Shiro wraps a hand around the omegas wrist and brings his fingers to his lips, 'Will you lose your job?'
The omega swallows, 'Yes.'
52
'Then no.' Shiro croaks, 'I'll lie.'
The omegas lips tremble, 'Don't.'
'Tell me your name.' Shiro begs.
'I can't.' The words are strangled, wounded, the fingertips press hard against Shiro’s mouth, 'Forget about me.'
Shiro doesn't know if he can.
The omegas lips tremble, 'Don't.'
'Tell me your name.' Shiro begs.
'I can't.' The words are strangled, wounded, the fingertips press hard against Shiro’s mouth, 'Forget about me.'
Shiro doesn't know if he can.
53
The attendant comes and takes the omega away.
Shiro packs in silence. He sprays a cleaner from the bathroom over the sheets.
He follows the attendant to a room where a satisfaction survey is placed in front of him.
Shiro packs in silence. He sprays a cleaner from the bathroom over the sheets.
He follows the attendant to a room where a satisfaction survey is placed in front of him.
54
In the space under 'were there any complications or unsatisfactory elements to your service?'
Shiro writes 'No'.
His fiancée picks him up in the lobby.
And Shiro leaves his heart behind.
Shiro writes 'No'.
His fiancée picks him up in the lobby.
And Shiro leaves his heart behind.
55
To be continued