Even the simple act of sitting up was a struggle for Lucas.
In reality, he was a strong, healthy young man in his twenties. But now, he was controlling a body that was on the brink of death, frail and aged.
Thankfully, this was just a simulator.
"You mean… the genetic enhancement serum?" Dotore seemed to have already guessed his thoughts, her expression unchanging. "You should know the side effects of the serum. In your current condition, once the effects wear off… you'll die immediately."
"Look at me now. What's the difference between this and being dead already?" Lucas said with a calm expression. "Let me use the last spark of my life to complete your final research."
"This isn't just my research. It's ours," Dotore corrected. "Even if I built ninety percent of this castle, without the foundation you laid, there would be no achievement today."
"Is that… a compliment?" Lucas smiled faintly. "That's rare."
"I'm just stating facts," Dotore continued. "I'll ask one more time. Are you really… sure about this?"
"Let's begin," Lucas nodded. "In this life, I've used others as stepping stones to climb higher. Now… it's my turn to be the stepping stone."
Dotore said nothing more. Silently, she took out the genetic enhancement serum and injected it into Lucas's veins.
As with previous uses of the serum, Lucas's body quickly began to change, reverting to his youthful prime.
He slowly stood up, the tubes attached to his body snapping off one by one.
"What a nostalgic feeling…" Lucas clenched his fist, feeling the strength of youth coursing through his muscles. "How much time do I have left?"
"One hour," Dotore pressed the timer in her hand. "Go. The Sustainer of Heavenly Principles has been waiting."
Indeed, the Sustainer of Heavenly Principles was seated in the laboratory at this moment.
But rather than a prisoner forced to undergo experiments, she seemed more like a bride on her wedding night, waiting for her groom to enter the chamber.
Like Dotore, she had long guessed what method Lucas would use to end his own life.
When she saw Lucas in his youthful form again, the Sustainer felt a wave of emotion.
Over the past thirty years, they had gone from being mortal enemies to forming a strange bond.
This period, though a mere fraction of the Sustainer's long life, had been more eventful than her entire existence.
"Both of our life forces are fading," the Sustainer slowly removed her robes. "This should be the last time."
"Yes," Lucas gently touched the Sustainer's cheek. "The last, and the most perfect, experiment."
"Can you grant me one final request?" The Sustainer closed her eyes. "Just once, don't call this method of continuing our genes an 'experiment.'"
"Then what would you like to call it?" Lucas asked.
"Use… the human way of referring to it," the Sustainer's breathing grew slightly uneven. "Those two words."
"Which two words?" Lucas pressed.
For the first time, a look of shyness appeared on the Sustainer's saintly face. She murmured, "Make… make… love.."
Lucas leaned down, his lips close to the Sustainer's ear, and whispered, "Let's have our three thousand seven hundred and sixty-ninth lovemaking session".
That night, the two most powerful lifeforms known in Teyvat unleashed the last of their vitality.
The entire Jade Chamber seemed to tremble, stirring the clouds beneath the moonlight.
---
In the cultivation chamber, a tiny speck of light floated within. It was the product of Lucas and the Sustainer's union, and it would become the final hope for protecting Teyvat.
"Embryo extraction successful." Even after achieving this historic success, Dotore's expression remained emotionless. "I will ensure its successful cultivation."
This was a mission she had no choice but to carry out, for the parents of this embryo would not last much longer.
After the effects of the genetic enhancement serum wore off, Lucas's body began to wither rapidly.
Meanwhile, the Sustainer's body started to gradually fade into transparency.
"Just as I suspected," Lucas said with a bitter smile. "Each Sustainer of Heavenly Principles is unique. If a descendant is born, the original body will dissipate."
This was also the main reason why research had progressed so slowly over the years.
"Do you have any final wishes?" Dotore asked indifferently. "Though I may not fulfill them."
"I want… to see Celestia one last time."
As he spoke, Lucas's body, now too frail to stand, was gently cradled in the Sustainer's arms.
"I'll take you."
The Sustainer, holding Lucas's shrinking body, walked out of the laboratory and step by step ascended to the Cloud Viewing Platform, the highest point of the Jade Chamber.
Below Lucas was the bustling capital of the Seven Nations, the great nation he had built. Yet the man who had stood at the pinnacle of Teyvat was now on the verge of death, his breath faint and his life hanging by a thread.
The Sustainer's body had already begun to dissolve into specks of light, scattering into the night sky. She looked down at the man in her arms, the one who had defiled her countless times, and said softly, "My final wish is… to take him to Celestia. Can you remove the Jade Chamber's barrier?"
"The Jade Chamber's barrier?" Dotore shrugged. "That was removed by him over a decade ago."
In other words, for over ten years, the Sustainer could have broken free at any moment, destroying the Jade Chamber in the process.
The Sustainer was stunned for a moment, then gave a helpless smile. "It seems my body wasn't the only thing imprisoned."
"Take me… to Celestia," Lucas's voice was barely audible. "Dotore, there's one more thing I need to ask of you…"
"I know," Dotore said casually. "I'll take care of the two sisters."
Lucas's eyes widened slightly, and he murmured, "So… you already knew?"
"I analyzed your genes. Of course I knew," Dotore sighed. "After all, you were never a good father."
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Author's Note: I just love this fic, I know I used the 3769 before too, but I'm gonna edit it to 3768 cuz 69 is perfect for the ending.