Title: the promise

A/N: For the Project: Teyvat zine! I absolutely love Darker than Black and Dainsleif and the twins fit in so well with the AU

Summary: The stars were fake. Dainsleif knew that, yet he found himself drawn to them all the same. In this world of contractors and dolls, of broken promises and murderous lies, it was a comforting constant. If only Lumine felt the same.

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i. Past

The stars were fake. Dainsleif knew that, and yet he still found himself drawn toward them, looking up whenever they took a break. Those twinkling lights above no longer represented light travelling across the cosmos, the memories of a star from eons in the past. No, instead each had an earthlier attachment.

"You really like the stars," Lumine said, interrupting his thoughts.

Dainsleif tore his eyes away from the false heavens to a sight closer to ground. Even for the night, it was dark in Liyue. The country was torn between the past and the present, between embracing modernity and clinging to traditions. Out in the countryside, stone lanterns were the only light for miles, their flickering light casting small pools of yellow-orange light. Fireflies drifted in the dark spots between, casting enough light to make out shapes.

Next to him, Lumine sat on a rock jutting out of a flower patch, her long white coattails and scarf fluttering in the wind. Her twin brother, Aether, leaned against her shoulder, his blond hair covering his eyes as he slumbered. Dainsleif didn't have to look up to know that the Viator star was dim.

Lumine looked at him expectantly and Dainsleif shrugged. "I would not say like."

She laughed lightly. "No, I suppose you wouldn't. Contractors can't feel, right?"

"We can feel," he corrected immediately. "We just don't let those feelings determine our actions."

"Sometimes I wonder…" Lumine murmured, gently tousling Aether's hair. She watched her brother affectionately, pulling him closer as he slept. "You're different from him."

"How so?" he asked, curious despite himself. They had been travelling together for weeks now, by order of the Abyss Syndicate, and while he had learned much of the twins during their long journey, he still couldn't get a bead on them.

Maybe it was because Lumine was an ordinary human, stubbornly joining the Abyss to stay near her brother. Maybe it was because Aether was oddly sentimental, often making decisions that prioritized his sister over the mission. The choices were rational, Dainsleif was certain about it, but they still rang more emotional than practical.

"I don't know," she admitted quietly, her finger twirling one of Aether's stray locks. "You're more distant than him. Less human."

"We're still human." Dainsleif looked at his hands, sensing the power coursing through them. It was a magic that belonged to fairy tales. "In a fashion."

"You just don't act like it." She looked up at him now, her eyes almost luminescent in the dim light. A gentle breeze ruffled her messy hair. "You're hard to get along with. You're cold. Aether hasn't changed much."

"That's because he has you," Dainsleif replied simply, peeking at their snoozing companion. There were few contractors that stayed with their family, fewer still who wanted to. Perhaps they would all be 'sentimental' if they had any earthly attachments.

Lumine smiled softly. "Maybe." She looked up now. Her eyes widened as she tried to take it all in. "I know they're not real stars, but they feel real. Is there really one up there that's Aether's?"

"Yes, the Viator." Dainsleif looked up for a familiar green star. "It's harder to find now."

"Because he's sleeping." Lumine's hand curled into Aether's shoulder. She frowned. "I don't like this. Why are you all connected with a star?"

A shooting star soared across the sky. Somewhere, a contractor had died. Dainsleif hoped it was one of their enemies. Their mission in Liyue would be a lot quicker if they didn't have to fight for every step they took. Every nation wanted to stake a claim. "No one knows, but it's probably the gates."

"The Archon gates," Lumine recited, no doubt repeating the Abyss Syndicate's training. "They suddenly appeared at the same time you got powers and the real stars disappeared."

"The gates probably caused all that." Dainsleif crossed his arms. It wasn't the first time he'd contemplated the strange quirks of fate and it probably wouldn't be the last. No one knew where the gates came from or why. No one knew why the stars now pulsed with the heartbeat of a contractor, letting those who could decipher its morse codes read the life of each contractor.

"If we secure them…do you think the syndicate could find the answers?" There was a slight wobble in Lumine's voice and he looked down to find her resting her cheek on her brother's head, hugging him close. "Even free you?"

"I doubt it," he replied honestly. "No one wants these powers to go away."

"Not even you? What about your obeisance?" Lumine looked up sharply. "Aether at least only has to fall asleep when he uses his powers. Yours deage you. At some point, you'll die."

"Maybe." Dainsleif admitted. While the payment for his powers was heavy, it didn't scare him. Nothing had, ever since he'd woken up with this ability. "Is there any need to live long?"

It was a truth, albeit a harsh one, and Lumine recoiled as if struck. "Of course there is."

"For you two, perhaps. Not for everyone." Dainsleif shrugged. "Still, I have no intentions to die just yet. I will be careful."

"That's not—" Lumine cut herself off, taking a deep breath to calm down. Her jaw tightened as she glared at him. "You follow contracts."

It wasn't a question, but he nodded all the same. "Provided the price is right."

Lumine snatched a white lily off the ground and held it up. "I don't have much, but here. You'll take care of yourself. You'll take care of Aether. You won't be reckless."

Dainsleif stared at the flower, surprised. "I thought you didn't like me."

"That's not what I said." She smiled. "You're hard to get along with, but we're partners now, right? I'd like to know you better."

She was genuine, he was certain of it, though he couldn't fathom the reason why. "That isn't a good deal."

Lumine didn't waver. "Then, I'll protect you too."

It still wasn't a fair deal. Despite all of her training, she wasn't more than a glorified servant, allowed to join as long as she guarded Aether when his obeisance forced him to sleep. Her abilities weren't worth more than a delaying action.

"Fine."

Despite all of that, he picked up the flower. She smiled at him and his lips twitched in return.

Maybe he wanted to get along with her better too.

ii. Present

The stars were fake. Yet, despite that, they were more constant than anything in Dainsleif's life these days. In the five years since that starry night in Liyue, Dainsleif had de-aged ten years, left the syndicate, and even started his own mercenary group. Not even his hands looked the same as they did the day before.

Yet, if he looked up, Viator would still be in the same spot, glowing as brightly as it had years ago.

"You still like the stars."

Even if that star was now connected to the hostile woman in front of him instead of her brother. Dainsleif studied the woman standing across the courtyard. If he hadn't known she was Lumine, he would have thought her a stranger. Her gaze was cool, impassive as she stared back, the emotionless eyes of a contractor.

That mission had changed everything, for better and for ill.

"I would not say like," he replied languidly, searching for a reaction.

Disappointingly, she didn't react, not even stiffening in her defensive pose. Her grip on her dagger remained tight as she pursed her lips. "You went missing."

"I did," he acknowledged with a slight tilt of his head. Fortunately, Mondstadt's streets were empty tonight, the park long abandoned by children. In the distance, the shadow of a statue kept watching, a man-made god protecting the city.

If they ended up fighting, there was no one to get caught in between.

Dainsleif stepped to his right, peeking around her to the man passively sitting on the bench. There was nothing of Aether's smile in the boy, nothing of his charm or his wit, but then again, there was nothing of Lumine in the woman across from him.

The rumours were true.

He frowned, unable to help himself. "Aether?"

Lumine followed his gaze. As soon as she looked at Aether, her expression softened minutely, her arms lowering slightly. Then, just as quickly, that moment of weakness was gone and she was impassive once more. "He's a doll."

A doll. A ghost of himself. If there was something worse than turning into a contractor, it was turning into a doll. Dainsleif couldn't recall the last time he'd met one with a wisp of personality, let alone memories of the past. The powers dolls got in exchange were minimal; they could see distant places through mediums, making their only use as scouts and spies.

There was a slight breeze and he wondered if the wind was Aether's eyes now.

Dainsleif dug his fingers into his palm, grounding himself on the sharp pain. "That's when you…?"

"Got his powers?" Lumine finished his question. Her eyes narrowed. "You were there for that."

"I can't remember it that well." It was a half-truth. He had images in his mind, flashes of memories of when they'd entered Liyue's gate. The region surrounding it had been a topsy-turvy mess, a place where the laws of physics didn't make sense. Dainsleif remembered Aether's glow, remembered Lumine's tears, remembered how he had dragged their bodies free of the dark gravity of the place.

But he hadn't really seen the aftermath. Not till now.

He took a step forward, focused on Aether's vacant expression. "I didn't think he'd end up like that."

Lumine stepped to the right, blocking him before he could get any closer. With her growth and his shrinkage, they were the same height now. He could clearly see the anger in her eyes. "I didn't either. Why are you here?"

Dainsleif lowered his hand. "Just passing through."

She snorted, raising her dagger once more. "Is it for the Barbatos gate?"

"No." His hair tickled his neck as the wind blew. Mondstadt was silent, except for the breeze whistling through the winding streets. "That gate's a lost cause."

"Then why?" Lumine's eyes locked on his. She tightened her grip on the hilt. "And why are you so young? What have you been using your powers for?"

Dainsleif remembered a younger girl worrying about him. There was none of her concern in this Lumine, none of her fear. "Does it matter?"

"If it gets in the way, yes," she replied bluntly, not even a flicker of worry crossing her face. Something in him twisted at the cold response. "So? Why are you here?"

"Visiting old friends," Dainsleif answered slowly, considering his next words. While Lumine was a contractor now, there were still shadows of her old self in her. He could reach her if he were careful. "The syndicate is using you."

Lumine laughed dryly. "They always were. Besides, it's mutual."

A practical response. It was one he'd given years ago too. "If it's safety you're looking for, there are other places to join."

"Thanks for the suggestion, I'll keep it in mind," she replied coolly, brushing a stray lock of hair out of her face. "Why are you here?"

"For you," Dainsleif finally said, carefully pulling a white lily from his pocket. He had preserved it right after Lumine had given it to him, using his powers to keep it in an eternal stasis. It glowed faintly, reminding him of moonlight and dew, of a flickering lamp and Lumine's smile. Cradling the bloom, he held it out.

Lumine's eyes widened and she lowered her dagger. "That's…" She glanced at him, then the flower. Reaching forward, she picked it up, studying it. "You still have it."

"Of course. We had a contract." Something in him uncoiled as she examined the flower.

"We did." Her voice grew colder and she looked up. "I don't need it anymore."

She turned her hand, dropping the bloom. Without thinking, he stopped time, freezing her in place. Quickly, he plucked the flower before it hit the ground. He brushed its petals delicately before looking up at her frozen face.

"We still have a contract." He reached up, cupping her cheek, brushing her hair out of her face. "And I will keep my end of it."

iii. Future

The stars were fake, and yet they were preferable to the dirty clouds that stretched out above Dainsleif in the Khaenri'ah Gate. The city itself had been destroyed when the gate appeared, leaving behind collapsed houses and abandoned cars. The remnants of a people no longer here. The air was full of dust, giving everything a hazy look.

"There aren't any stars here," Lumine murmured, rubbing her arms as she looked up. There was a faint tremble in her voice, a faint sense of fear, and Dainsleif wondered if that was her or if that was the gate's influence. "I didn't think it'd be so…dead in here."

"The gate obscures the sky," Dainsleif explained, picking up a torn teddy bear. Its button eye dangled by a string.

She raised a brow. "Doesn't the gate create the stars?"

"Maybe." Dainsleif looked up at the cloudy skies. Faintly, he could make out a single star, and he wondered if that was a real one from his childhood or just another fake. If only he had enough time to explore the possibilities. If only he had time.

But he was a child now, maybe eight at most, and there was only enough time within him for one last trick.

Aether tugged on Lumine's shirt, his head bowed as he stared blankly at the ground. "I can't see."

Dainsleif snapped his attention to Aether. "Don't try to use your Sight. It'll only drive you mad."

Lumine gently grasped Aether's hand, keeping him close. Years ago, it had been the reverse, Aether holding Lumine as they explored the Morax Gate. She glared at him. "You didn't warn us."

"I told you it would be dangerous," Dainsleif countered calmly, dropping the bear. "You're the ones who followed me."

"Don't act like that wasn't your plan," she sniped, snorting. "You left plenty of clues."

"Fair enough." He studied her profile. Anger was etched on her face, but also fear. But also hope. Perhaps there was still a chance. "Did you leave the Abyss?"

Lumine frowned, looking away. "Yes. You were right, they were too dangerous to deal with." Annoyed, she kicked a broken bottle and watched it roll until it hit a brick wall. "I thought nothing was left of Khaenri'ah."

"The people, no." Dainsleif crossed his arms. The place looked like it was full of ghosts, though that was an irrational thought. Despite the new existence of magic, there still was no such thing as the supernatural. "They suddenly vanished when the gate appeared."

"You vanished once," Lumine pointed out bitterly, turning to him now. "This doesn't look like a 'gate'."

He ignored the barbed attack. "It's not a physical gate. A metaphysical one. It might be possible to see the real stars if we could clear the clouds."

Lumine raised her hand. Wind swirled around her, her clothes ruffling rapidly as the gust grew in pressure. Aether tightened his grip on her hand. When she finally unleashed it, it blew up to the clouds before dissipating entirely. She frowned.

Before she could raise her again, Dainsleif grabbed it. "Don't. You don't know what the gate could do. It might erase our existence entirely."

She yanked her arm free. "Fine. Why did you call us here?" Her eyes narrowed. "You said you knew how to get us out."

"I do." Dainsleif stepped forward, holding out his hands. "I'll tell you how, after."

She eyed his hand suspiciously. "After what?"

"I just need to check something," Dainsleif lied, taking a deep breath. Before they could react, he grabbed Lumine's and Aether's wrists. His powers churned as he activated them.

"What are you doing?" Lumine shouted, trying and failing to free her arm from his iron-clad grip.

"Keeping my end of the promise." Dainsleif felt his power course through him and into them, felt their time reverse, felt himself shrink in response.

Aether's powers had flowed into Lumine at the gate. It was only at the gate that they could flow back out.

Aether stood straighter, his eyes glimmering with awareness. "Where…I…"

Lumine gasped, tears forming in her eyes. Already, her emotions were returning. With her free hand, she grabbed Aether. "Aether! You're you."

"I…I am?" He looked perplexed, still processing the sudden dump of sensations and memories.

"Yeah, you—" Suddenly, she snapped back to Dainsleif. Her eyes widened and she pleaded, "You can't! Dainsleif!"

He smiled, his grip weakening as the last of his strength surged out of him. The flower in his pocket tumbled out, landing at her feet as Dainsleif fell backwards. "It's fine."

Aether was back. Lumine was back.

He'd done it. It was more than enough.

Dainsleif could feel himself shrinking, de-aging, his body going backwards until it wiped itself out. Above him, all he could see were those yellow clouds. If only he could have died under the stars, real or not. If only he could have said something more.

Lumine screamed and a surge of power hit Dainsleif before he landed on the ground.

Somewhere above, a new star appeared.