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Lily Evans has been hiding that she’s an Omega since she was fourteen. Luckily, she blossomed when she was in the Muggle World over the summer. It hadn’t taken much time at all to sneak into Diagon Alley one afternoon, so the Ministry wouldn’t be able to pick up her trace. She disguised her use of underage magic, the scent-blurring spells, beneath the wards of Diagon Alley and has never taken them down since.
It’s fine. She’s fine.
For all that Omegas are revered in pureblood society, for they can bear many strong heirs safely, they aren’t really safe unclaimed. Omega-napping is considered extremely rude, but it’s not illegal. Not as long as it ends in a Mating.
Lily is terrified that one of the Death Eater Slytherins will steal her away. So she keeps her mouth shut and her scent to herself.
“I’m not going to Mate a Death Eater,” Lily promises herself. She will throw herself at Alpha Heir Potter’s feet first.
She’s managed to suppress and overcome the majority of her instincts through sheer force of will. But seeing several of the older Slytherins trying to forcefully usher Master Regulus Black down into the dungeons isn’t something that she can ignore. He’s just a pup!
Lily knows that Alpha Heir Sirius Black is up in Gryffindor Tower finishing an essay so he can spend the weekend with his little brother. He’s not here to watch over Regulus, as he usually is.
“No. No. No,” Regulus whimpers so softly she almost can’t hear him.
If it were anyone else, she would go inform a professor instead.
But Lily can’t abandon Regulus to whatever the Death Eaters want with him, not when she can scent terrified-pup in the Entrance Hall. Not when she overheard him whimpering in Sirius’s arms just last week, terrified he would be enslaved to the Dark Lord by his housemates kidnapping him.
Her chest aches fiercely enough to make her cringe. Her instincts riot against her control.
“Am I really going to—?”
Regulus floods the Entrance Hall with terror-fear-somebody-save-me.
Lily takes a deep breath, cancels the spell that muddles her scent, and gives an Omega-chirp. Everyone in the Entrance Hall spins to face her. She only debates her next action for a moment, because she knows if she goes through with it the whole school will believe by morning that she’s Alpha Heir Sirius Black’s Omega.
But Black-pup is sad and scared, and Lily can’t stand the smell of it.
She holds out her hand, stares right at Regulus, and gives the sharp bark that demands a pup’s presence. Regulus sprints to her side. None of the Slytherins try to stop him.
“Good pup,” Lily whispers very quietly, before rubbing her cheek against his curly black hair.
Regulus is non-verbal at her side, eyes wide, and shaking as she wraps her hand around the back of his neck and leads him to the grand staircase.
Lily allows her instincts free reign. She’s been able to hold back in the past because Sirius was always there to care for the pup. Sirius isn’t here now. That’s okay, though. Lily can handle this.
She doesn’t let go of the pup until she needs to pace three times across from the tapestry on the Seventh Floor; doing so will open a secret room, the room she has hidden her Nest in. The door appears and Lily ushers Regulus inside before closing it behind them.
Regulus walks right over to the edge of her Nest. His hands hover over the mound of pillows and blankets, but he doesn’t touch it. The pup-cry that spills from his lips is heartbreaking.
The ache in Lily’s chest intensifies to the point of discomfort. It’s never happened to her before, but she knows the signs. She has read all about it.
Her actions today will have far-reaching consequences, but she can’t regret them.
Lily Transfigures their clothes into comfortable pajamas, gets in her Nest, settles firmly against one wall of it, and beckons Regulus inside.
Regulus crawls in the Nest, his eyes wet and body shaking. He stops before touching her. His gaze is locked on her pajama top, which is darkening in patches from the breast milk she’s leaking. It’s a biological and magical response to pureblood pups being in danger, a way to soothe and comfort them and prove they’re safe.
“Pup?”
Regulus makes a sound of such begging-longing that it’s torturous to her senses. Please-please-love-protect-me spills out of him in waves.
It’s so genuine of a need, how could she possibly refuse?
Lily cups his face in one hand and leads his mouth down to her right breast, after unbuttoning her pajama top. Regulus latches on with wonder, curling up at her side. He’s barely half her size, having not hit his second magical growth spurt yet. He’s so small that if she didn’t know for a fact Sirius ensured he had enough to eat every day, she would think he was starving.
As Regulus burrows against her chest and suckles, she pets his hair. It’s so soft. He’s a beautiful pup. It’s criminal how the bitch who whelped him treats him.
The sound of the door opening startles Lily into wrapping her arms around Regulus, dragging the nearest blanket over him, and flashing her teeth. Just as she’s about to let loose a vicious growl, she recognizes the intruder’s scent.
“Alpha Heir Black.”
Sirius stands in the doorway, a large piece of parchment in his hands. Lily knows it’s the Marauder’s Map; the Marauders are awful at keeping secrets. He must’ve seen her make off with Regulus and followed them to see what was going on.
“You have my brother-pup at your breast, Omega.”
Even though her chest is covered by the blanket, Lily blushes and says, “Yes.”
Sirius’s scent becomes overwhelming. He enters her Nesting room and closes the door behind him. He prowls across the room, his scent getting headier every second.
“Mine,” Sirius growls possessively as he stares down at her.
He’s right. By claiming and feeding his Black-pup, Lily’s made herself part of his personal pack. If Sirius desires … her actions can be considered an Offer of Mating.
“Yours.”
Lily lowers her gaze and leans her head aside, baring her neck to him. Sirius rumbles with pleasure and enters the Nest. He rubs the bottom of his chin on the top of Regulus’s head, where it peeks out of the blanket, and then nuzzles Lily’s neck until she smells of Black Pack and nothing else.
Lily’s face burns scarlet as Sirius curls around her in the Nest, protective-family-keep-forever-mine wafting off him. If he glances down at the angle he’s at he’ll be able to see down the blanket. He doesn’t, though. He closes his eyes and continues to nuzzle against her neck.
“My Omega. My pup. My pack.”
Sirius will let her go after the universe has collapsed in on itself. To touch her now is to die.
She’s the Omega Heiress of the Black Pack.
Lily is finally safe.