Archive of Our Own ^beta

“You think I’d lie to my little sis?”

“Even the sound of your footsteps takes me right back. As a warrior, as a traveler… as my little sister…”

“If this is about strength of blood, what could possibly stop us?”

Lumine could hardly believe it. After entering the secret chamber, she kept pinching herself discreetly to make herself realize she wasn’t in a dream… like so many she’d had before. That maybe she had never gotten up from her bed at the tavern after all, never taken a walk across half of Nod-Krai, and that everything happening was only in her imagination. Because it’s how surreal it truly felt, after so many years apart, for her to be adventuring next to her beloved brother again.

The bittersweetness was almost enough to sting her eyes, but she tried her best to tamp down her roiling emotions. She wanted to enjoy the thought of their reunion, temporary as it was.

Despite it all, it comforted her to hear Aether speak so fondly of their bond again. She wanted to believe and have faith in him, and their ties. She meant what she had said—she had made peace with and accepted him all the same, even if she couldn’t understand his intentions and plan. Yet, it did little to quell her doubts if he even still cared about her after all this time. Their last meeting had confused and weighed on her heavily.

But Aether did not seem any more open to giving her answers than before. Staring at his back, following him through the paths of the chamber, she wondered what this strange feeling was. The abyssal energy seemed more potent on his being than in the past—perhaps that’s what made him feel distant from her.

Not to mention, she reminded herself, they’ve been separated for far too long, longer than she can remember, longer than she even truly knows. He was still her Aether, and yet she didn’t know anything of what he’d been through. She swallowed painfully. She didn’t want to cry, not right now.

Perhaps her melancholic silence permeated the air so much, it caused Aether to look back at her over his shoulder.

“Lumine?”

You’re the only one who calls me that in this world, she thought. It both warmed and hurt her heart to hear him say her name.

“What’s wrong?”

Lumine wanted to laugh. But it made sense he’d ask such a silly question, after all. Just as Aether was slowly becoming a stranger to her, no matter how hard she fought it, she was probably just as unfamiliar to him now. Aether wasn’t the only one who had changed, these past years. Maybe he really didn’t understand her at all, anymore. She would always remember the hurt from their first reunion in Teyvat, when the only words he’d had to say to her were about Dainsleif, of all things.

“Nothing.”

He frowned, looking into her face, as she avoided his gaze.

“Tell your big brother,” Aether insisted, moving closer.

Lumine closed her eyes. “...In all my dreams where we meet again, we’d hug and laugh. I’d run into your arms and you’d catch me, like always. We’d eat together, celebrate festivals, travel together.” A tear finally escaped. “You’re right here in front of me, but it still feels like there’s so much separating us, even now.”

“It’s always only ever been about us,” he repeated.

“That’s what you told me, last time,” she nodded. “But I don’t understand it.”

“You will. Always remember, no matter what, you’re what’s most precious to me,” he softly assured her.

She felt his hand on her cheek, gloved thumb brushing away her tears. She opened her eyes, to realize how close Aether had gotten. Something inside of her shivered, but she didn’t know what it was.

“What can I do right now, to remind you?” he whispered.

Her glassy eyes met his. Does he remember? she wondered, her face inching closer to his.

As if he heard her thoughts, he caught her lips, effortlessly, like it was second-nature to him. Once upon a time, it had been.

Lumine’s arms came up to wrap around his shoulders in response, as she surged forward. Then, like in her dreams, Aether’s arms caught her around her back, holding her close to him.

She was so caught up in the bliss, feeling like everything was right, even if just for a moment, she didn’t notice Aether’s palms moving down her waist.

Lumine yelped, pulling back her head, when she felt an intense grip on her hips.

“Aether?” she asked, feeling breathless.

“Yes?” His face was so innocent, in spite of where his hands were.

“W-what…”

“What’s wrong, Lumine? This is not unfamiliar territory for us.”

She bit her lip. Aether wasn’t wrong. They were two halves of a whole, soulmates in every way, loved each other in every form, the way no one else could ever hope to understand between them. There were no barriers to their bond.

He caught her in another kiss, this one more forward than before. Head feeling muddled, she stopped trying to make sense of it, and reciprocated, causing Aether to smile against her lips, and his hands began to wander lower.

Completely distracted, she didn’t even realize he’d taken off his gloves and pushed aside her bloomers, until she felt a warm digit slide along her slit.

He swallowed her gasp, before pushing a finger inside. It wasn’t long before a second joined, then a third. Her walls clenched instinctively but she forced herself to relax, letting him stretch her. He found a rhythm, sliding in and out, while the pit of Lumine’s stomach coiled tighter and tighter, as she squirmed in his arms. It was probably the heightened sensitivity from finally being with Aether again, but with just a few pumps, she found her release.

“That’s my girl,” he murmured into her hair, while she sagged against her brother for support.

He pushed her against the flat wall of the chamber, the cool stone a shock against her heated skin. He moved to pull down her bloomers but she held his arms in place.

“Here?” Lumine panicked. It wasn’t the most public area, but it wasn’t private either. There was no guarantee the Frostmoon Scions wouldn’t happen upon them.

“I placed an Abyssal barrier around us, the moment I kissed you,” he placated her. “I would not risk anyone else seeing you like this. This…” he gestured at her glowing and disheveled state, “You are only for me, Lumine.”

She hesitantly relented, stepping out of her bloomers and undergarments, leaving her bare underneath her dress.

Aether aligned himself, before pushing his full length inside of her all at once, wordlessly. Lumine cried out in pleasure, feeling her walls being stretched for the first time in so long. Besides the physical gratification, it also brought her a sense of completion she’d been missing since before they came to Teyvat.

“I’ve missed you, Lumine,” Aether panted, his voice low and guttural. It sounded different, like the abyssal energy he used was affecting him somehow. It was hard to think though, feeling so full. She clung to her brother, as he lifted her legs to hook around his waist.

He kissed her again, causing her to melt and lose focus. Each time, it felt overwhelming to her senses because of the surreality. This time, it was harsher and more possessive.

And it wasn’t just his kiss, Lumine realized belatedly through the haze of pleasure. His grip on her thigh and hip would definitely bruise her, later on. The way he snapped his hips to hers felt feral, the pace dizzying with deep, long strokes. If he hadn’t stretched her earlier, it would have hurt. It must have been because of their separation—it must have affected him as much as it affected her, making him desperate and domineering. Blinking back tears, she clung to him tightly, because when would be the next time she could have this chance?

He moved her scarf out of the way, to bite at the crook of her neck. This pushed her over the edge, as she fluttered along his length, crying out for her brother. As the aftershocks ran along her entire body, she felt Aether bury and spill himself deep inside of her, warm and thick. He continued fucking her through it all, his release leaking out, leaving her trembling and euphoric.

As the two of them came down from their high, she looked for his face, to ground herself, to assure herself this was real. Instead of being comforted, Lumine found herself slightly unsettled. Aether’s expression was not entirely strange for him, but it still had a foreign air to her. His smile was almost smug, his lidded eyes boring into hers.

“You belong to me, Lumine,” he asserted, again.

Unsure how else to respond, she nodded.

Bedding the sister of the Abyss Prince hadn’t quite been on his agenda at the outset of his deceit, but Rerir was nothing if not an opportunist. And he could not deny he enjoyed it. Lumine was a beautiful creature, glittering and transcendent—he could feel how everything about her was not of this world.

He held some respect for her, with the knowledge he’d gained as he bided his time, regaining his strength.

He had simply meant to trick her with some rose-tinted white lies. He would get what belonged to him, and he could give her a bittersweet reunion with her beloved brother. A mutually beneficial arrangement, in his view. He hadn’t intended for it to go as far as it did, but if all went according to plan, she would never be the wiser. Some tender memories with her brother was something even he wouldn’t be so cruel as to deprive her of.

His performance was mostly based on the memories he’d peered into, in her consciousness. And yet, he had not realized the depth of the siblings’ relationship. He had no concern for morality—not anymore, as one of the Five Sinners, of course. Who was he to cast judgment?

There were moments he lapsed, and he could sense those moments were when Lumine hesitated. Of course, they were twins. No other creatures in the vast universe would know them better than each other. His ruse needed to be watertight. His shapeshifting was immaculate, there was no doubt. He had much practice pretending to be others, as well.

Lumine was the only one who ever held suspicion of him.

He suspected her desire for this fantasy-come-true also blinded her, else she would not have come along so sweetly and blindly.

Selfishly, Rerir marked her. It had been a long time since he’d felt warmth like this, and Lumine’s was exquisite.

As they continued their way through the corridors towards the Moon Marrow, he marveled at how she had fit him perfectly, wondering if it was in part due to her body being made for Aether’s, and his for hers. Two halves of a whole, after all.

When they had reached the end of the chamber, the Moon Marrow lay before them, gleaming and incandescent.

Lumine remembered the profound sense of foreboding and how it only worsened when she heard the last words Aether spoke to her before the fog came and she lost consciousness.

“Go get it for me, Lumine. It belongs to me.”

And yet, when Flins had saved her from the encroaching Wild Hunt, asking who it was she had been with, she answered, without hesitation, “That was… the person dearest to me.”