Secret Nemesis | Aether x Reader

Prologue

"Princess," you bowed before opening the door and entering the throne room of the castle. "I come and serve."

Sitting before you on the throne was a blonde-haired and brown-eyed teenage girl wearing a white dress embroidered in gold. In front of her was an abyss herald with one knee to the ground as he held out his arm to summon a see-through portal. Lumine's eyes grew dim with each passing second as she looked into the portal.

"You may leave," Lumine dismissed the herald who created another portal to disappear. "You can drop the formalities now y/n."

"Princess Lumine," you smiled as you greeted your savior.

Around 7 years ago, Lumine had found you nearly dead on the ground of Fontaine. Taking you under her wing, she saved and helped you, and ever since that day, you had decided to serve her as a thank you for saving her.

"Just call me Lumine," she closed her eyes thinking that no matter how many times she had told you to drop the formalities, you wouldn't. "Well anyway, how have you been y/n?"

"Just some training here and there," you shrugged. "How are you doing Princess?"

"I'm fine," Lumine sighed, fiddling around with a locker that she held onto. "Just a lot of things to think about."

"Is there any way I can help you lessen your load?" You asked, concerned for your savior's health.

Lumine smiled with your awe-inspiring loyalty, "That's the reason why I called you, I have a mission for you."

"Ooh, what's the mission this time?" Your eyes sparkled with excitement.

Every time Lumine sent you on a mission, you were excited since you had the opportunity to explore Teyvat and adventure around. And not only that, you were genuinely happy to be of help to the person that you looked up to. You wanted to serve her to the best of your ability, thus the reason for your constant training.

You owed your life to her and so, you now promised to dedicate yourself to her. Although Lumine had always rejected your offers to serve her, you promised yourself that you would fulfill a personal goal of being of use to the Princess of the Abyss.

"I want you to watch over my brother, Aether" Lumine told you, her eyes growing gloomy when she mentioned the one person most important to her. "If there is anyone that can protect him in my place, it is you. You are the only one that I can trust with this responsibility."

"Your brother?" You wondered since she had never shown you what he looked like before and much less talked about him.

"He's my twin," Lumine explained as she called you to her side. "He looks just like me but instead a boy version with long hair."

Walking up to her, she took the locket that she was holding on to and showed you the picture in it. Two people hugged each other - both smiling in pure bliss, one was Lumine and the other, you suspected was her brother.

"Those were happy days," Lumine muttered, her face crestfallen. "It was the two of us, we always stayed together. Home is with him."

"I hope that sometime you can regain that joy," you told Lumine, understanding just how much her brother meant to her.

"Me too."

"What shall I protect him from?" You continued on, hoping to lift up Lumine's spirits someway by changing the topic.

Lumine thought for a moment before answering, "I just want you to watch over him in my place because I can't do it myself."

Seeing Lumine's despondent expression, your heart tightened with a burning passion. You would protect Aether with your life. Nothing would harm him under your watch. Looking at your savior, you wanted her to smile again and not be plagued with such worries. No matter what, you would not fail.

"Understood," you bowed in respect before leaving the room. "I swear that I will protect him with my life since he is the one most important to you."