At six in the morning, Artoria woke up at her workbench in the basement.
She had slept for four hours slumped over the spread-out design blueprints, the assembly drawings for the transmission system pressed against her cheek. Morning light slanted in from the high window, illuminating the complex gear ratios, torque curves, and kinematic equations on the papers.
She sat up and stretched her stiff shoulders. On the workbench, the energy core slept quietly in a specially made shielding box, its pale blue glow pulsing softly through the observation window. The complete titanium alloy skeleton stood silently in the morning light, waiting for muscle and nerve.
Today, the manufacturing of the transmission system would begin.
She walked to the skeleton and lightly touched the ball-and-socket joint of the hip. This was the hub of movement, needing to withstand the maximum load while providing the most flexible range of motion. According to the design, every joint had to integrate miniature servo motors, planetary reduction gear sets, torque sensors, and temperature monitoring—a total of 24 major joints and 72 minor joints.
"Let's start with the hip joints," she whispered.
She took out pre-fabricated servo motor components from the material box—Japanese-made high-torque miniature motors, three centimeters in diameter, with an output torque of 5Nm but weighing only eighty grams. The channels provided by Tony had allowed her to obtain laboratory-grade prototypes, with performance 30% higher than commercially available versions.
Assembly required precision operation. She brought up the system interface; today's Echoes had refreshed:
honkai impact 3rd: Bronya Zaychik (Available, 12 hours) - Precision Operation/Calculative Intuition
Genshin Impact: Keqing (Available, 12 hours) - Electro Element Precision Control
Super Seminary: Rose (Available, 12 hours) - Spatial Positioning
Miss Kobayashi's Dragon Maid: Thor (Available, 12 hours) - Forging Instinct
Cells at Work!: Platelet (In Cooldown, 4 hours remaining)
She chose Bronya. Her figure shifted amidst a faint light, silver twin-tails and tactical goggles appearing as a stream of data flickered in her gray eyes. In Bronya's form, she possessed top-tier mechanical operation intuition, her finger control precision reaching the micrometer level.
The work began.
She installed the servo motor into the hip joint's custom housing and connected the planetary gear set. Sixteen miniature gears had to mesh precisely within a four-centimeter diameter space, with the backlash controlled to within 0.01 millimeters. Any deviation would lead to noise, wear, and eventual failure.
Bronya's 'Understanding and Reconstruction' ability allowed her to intuitively perceive the mechanical properties of every part. She adjusted the gears, tested the meshing, applied specialized grease, and then locked the housing. The entire assembly process was as fluid as if practiced a thousand times.
By the time the first hip joint was finished, it was nine in the morning. She installed it onto the left hip bone of the skeleton, connected the control cables, and performed basic tests.
Upon switching on the power, the servo motor emitted an almost inaudible hum. She sent commands through the test program—flexion 15 degrees, extension 30 degrees, internal rotation 20 degrees, external rotation 25 degrees. The joint moved smoothly without sticking or backlash.
The torque sensor readings were stable, and temperature monitoring was normal.
"Passed," she recorded.
The morning's work was highly efficient. In Bronya's form, she completed the assembly and testing of both hip joints, knee joints, and ankle joints. By twelve noon, the main transmission system for the lower limbs was basically formed.
She deactivated the transformation and rested for a moment. Lunch was a simple energy bar and functional drink; as she ate, she brought up the pattern left by the deep-sea luminous entity last night on her computer.
That equilateral triangle, with rotating lines extending from each corner.
From last night until now, she had been pondering the meaning of this pattern. A triangle is a stable structure, while rotating lines represent movement and change. Combined... Dynamic balance? Periodic cycles? Or an expression of some spatio-temporal relationship?
She input the pattern into mathematical software, attempting to analyze it using geometric transformations. The software could not recognize it—the mathematical foundation of this pattern exceeded the scope of standard geometry.
But her intuition in Bronya's form gave her a hunch: this wasn't a two-dimensional pattern, but a projection of a three-dimensional structure. Those rotating lines weren't on a plane, but in space, rotating around an axis of the triangle.
"Stereoscopic projection..." she murmured.
If this hunch was correct, then what the luminous entity was expressing wasn't a planar relationship, but a spatial one. The triangle was the base point, and the three rotating lines extending from it were... Dimensional axes? Timelines? Or some kind of connection path?
Her phone vibrated; it was a call from Tony.
"How's the progress?" he asked. "I've monitored that your energy readings have been stable, which is good. Also, the S.H.I.E.L.D. observation point added more equipment this morning, looks like they're setting up some kind of array. Want me to 'interfere' a bit?"
"Not for now," Artoria said. "As long as they don't cross the line."
"Alright. Also, about that pattern from last night—I had Jarvis analyze it, and the conclusion is quite interesting. Jarvis thinks it's a 'coordinate marker.' The triangle is the origin, and the three rotating lines are displacement vectors that change over time. Simply put, it's marking a location, but that location is moving."
"Moving?"
"Yes. According to Jarvis's simulation, if you interpret this pattern as the trajectory of an object in three-dimensional space, it describes a... periodic back-and-forth movement. Starting from a base point, moving along three different paths, and finally returning to the base point, repeating in a cycle."
Artoria stared at the pattern on the screen. Periodic back-and-forth... like describing some regular movement, or perhaps, a state of existence.
"It might be describing itself," she said.
"What?"
"The state of existence of the deep-sea luminous entity. The triangle is its 'base point' or 'anchor point,' and the three rotating lines are its activity trajectories in different dimensions or points in time. It's telling us its behavioral pattern."
There was silence for a few seconds on the other end of the line.
"Makes sense," Tony said. "But why tell us this?"
"A farewell," Artoria whispered the word. "Or... a preview."
The call ended. She sat at the workbench, looking at the pattern, then at the calm sea outside the window. If the luminous entity really was going to leave, then this pattern it left behind was the final message before farewell.
In the afternoon, she continued her work. This time it was the upper limb transmission system—shoulder joints, elbow joints, wrist joints. These joints required a larger range of motion and finer control, making their structures more complex.
In Bronya's form, she worked until six in the evening. She completed the assembly of both shoulders and both elbows, then began processing the most delicate hand joints.
The hands of a humanoid robot are one of the most complex parts. Each hand has 27 degrees of freedom—3 for the thumb, 4 for each of the other four fingers, and several auxiliary joints in the palm. To create a hand capable of precision operations required the ultimate craftsmanship.
She spent three hours and only finished three fingers of the right hand. The sky had darkened; she turned on the work lamp and continued.
At nine at night, the right hand was complete. The five titanium alloy fingers glinted coldly under the light, each joint capable of independent movement, with miniature force sensors integrated into the fingertips. She performed tests—clenching a fist, extending, finger opposition, and lateral pinch. The movements were smooth, and the force was controllable.
"Passed," she recorded.
Just then, her wristband vibrated. It wasn't an alert, but a regular short vibration—a non-emergency communication from S.H.I.E.L.D..
She picked up; it was Coulson.
"Miss Artoria, the deep-sea anomaly is undergoing a significant change. Energy readings are rising sharply, but the distribution range is shrinking. It seems to be... condensing."
"I'll take a look."
She walked out onto the terrace. Under the night sky, an astonishing scene was taking place on the sea surface.
The luminous entity was no longer a halo of light; it was shrinking, condensing, becoming brighter and brighter. The pale blue light turned to a brilliant white, its brightness intensifying until it illuminated the entire sea area. In the center of the light, complex geometric structures were dimly visible, rotating and reorganizing rapidly.
Then, the light began to rise.
Not surfacing to the water, but upwards, toward the sky. A pillar of light about ten meters in diameter rose from the sea surface, shooting straight into the night sky. Inside the pillar, countless points of light moved rapidly, arranging themselves into complex patterns—exactly the combination of the triangle and rotating lines Artoria had seen last night, but this time it was a complete dynamic display.
The triangle suspended stably in the center of the light pillar, and three lines extended from the three corners, beginning to rotate. But the rotation wasn't planar; it was three-dimensional—the three lines moved on different dimensional planes, forming complex trajectories.
Then, the three lines began to glow, shooting out three slender beams of light pointing in three directions:
One pointed toward Artoria's cottage.
One pointed toward Tony's Villa.
The third... pointed toward the deep sea, toward the location where the light pillar had risen.
"It's marking," Artoria said softly.
Marking her, marking Tony, marking itself. The triangle was the relational structure connecting the three points.
The light pillar lasted for about three minutes. Then it began to change—the three light beams retracted back to the triangle. The triangle itself began to rotate, faster and faster, finally turning into a sphere of light.
The sphere of light slowly rose, higher and higher. Until it became a bright point of light in the night sky, like a newborn star.
Then, the point of light flickered three times.
Bright, dim, bright, dim, bright, dim.
Like a farewell.
Finally, the point of light suddenly extinguished. The night sky returned to darkness, and the sea surface became as calm as a mirror. The luminous entity had vanished, all energy readings returning to zero as if it had never existed.
But Artoria knew it had left something behind. That pattern, those markers, that understanding.
Her wristband vibrated, and Tony called, his voice unusually serious: "It's gone."
"Yeah."
"But it left a message. That pattern, I had Jarvis do a full analysis—the three rotating lines, if interpreted as time axes, describe the intersection of three points in time. Past, present, and future. The triangle is the stable point of existence, connecting the three times."
"What is it saying?"
"It's saying..." Tony paused, "'I have observed your past, I am in your present, and I will appear in your future again.' It's a farewell, but also a promise."
Artoria looked toward the night sky. At the position where that point of light had disappeared, only ordinary stars were twinkling.
"What else did it say?" she asked.
"In the deepest part of the pattern, a set of coordinates was hidden," Tony said. "Not Earth coordinates, but... some kind of high-dimensional spatial positioning marker. Jarvis can't fully analyze it, but can confirm it's a type of positioning beacon. When it wants to come back, it can use this beacon to find us."
"So it will return."
"Sooner or later," Tony's tone relaxed a bit. "At least we know it's not hostile. And... it chose us as its contacts. You, me, and this sea."
The call ended. Artoria stood on the terrace, the sea breeze blowing her long hair. The night sky was serene, the light from the deep sea was gone, but that sense of connection remained—fainter, but clearer.
It wasn't a threat; it was a passerby, an observer, a visitor from the future.
She returned to the basement. On the workbench, the unfinished left hand waited under the light. The energy core pulsed quietly in the shielding box. The complete skeleton stood silently in the shadows.
She opened her notebook and wrote on the latest page:
"Deep-sea luminous entity departed, leaving a farewell message and a return beacon. It marked me, Tony, and this sea as future connection points. Non-hostile, an observer and a promiser."
"Transmission system progress: Lower limbs complete, upper limbs in progress. Right hand complete, left hand remaining. Tomorrow's goal: Complete the entire transmission system, begin nervous system layout."
After writing, she walked to the skeleton. In the morning light, the silver-white metal surface gleamed with a delicate luster. The assembled lower limb joints were firm and reliable, and the right hand's fingers were exquisite and flexible.
She lightly touched the chest of the skeleton, where the cavity awaited the installation of the energy core.
"Soon," she whispered. "Your body is taking shape, your heart is beating, and your hands will be able to touch the World."
The skeleton remained silent. But in the morning light, those installed joints reflected tiny spots of light, as if in response.
Outside the window, the lights of the S.H.I.E.L.D. observation point still flickered. In the distance, Tony's Villa was lit up. The sea surface was as calm as a mirror, but there was no more light in its depths.
In this World returned to peace, she continued to manufacture her companion.
One step at a time.
The deep-sea arc had temporarily concluded, but the promise was made.
In the future, the light will return.
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