What makes up a living being?
Many things do. Blood, hair, skin, lungs, and a variety of other organs function together to work together to keep the creature alive.
Although every organ is important, three organs take precedence over everything else.
The brain, heart, and the soul.
Every being has something along those three.
The brain gave the creature intelligence, the heart gave it life, and the soul gave it personality.
Only when these three things were satisfied did life emerge.
Hephaestus spent a year making the heart and veins for his metallic creature. Making the mechanical heart a spherical core that would pulsate with small pistons pumping in and out mimicking the movement of a heart. Using lava as a fuel source for combustion, it would move indefinitely as long as the creature consumed coal or lava. This superheated blood of the creature would inadvertently harden the bones which was a net positive.
Hephaestus spent another year on the brain of the metallic creature. As a creature with intelligence, he used delicate clockwork-like mechanisms for the brain, creating a multitude of interlocking gears to function like a calculator. With a few more adjustments, Hephaestus made it so that it could also store information in its brain.
The last thing Hephaestus worked on was the soul. How could he create a mechanical soul? Was it even possible to artificially create a soul?
Perhaps he could ask his uncle Hades, the god of the underworld but that would mean Hephaestus would have to expose his existence to the gods. Hephaestus wasn't ready for that yet.
After two years of tinkering and brainstorming ideas on how to make a soul, Hephaestus came to an epiphany.
The soul wasn't something to be created, but something that would enter a suitable body. Babies would obtain a soul during pregnancy as they developed and matured. So perhaps if his creation was suitable to host life, it would gain a soul.
Seeing no other option, Hephaestus decided to test his theory out.
He first made his creature smaller, more infant-like. He made it so that the creature would be able to grow slowly by adding more parts. He also made an egg-like structure made of metal and placed the creature inside. Connecting the creature's artificial veins to the sides of the walls, Hephaestus then heated the metal egg near the pool of lava and waited.
After many months of waiting, just on the dawn of Hephaestus's twentieth birthday, the egg cracked to Hephaestus's great joy.
With a small squeak, a mechanical creature made of iron peaked its head out. It stared curiously at its environment before settling its gaze at Hephaestus who watched on quietly with a sense of amazement.
The creature struggled before eventually eating the metal egg encasing it and revealing its body.
Reptilian scales made of iron, still soft from being hatched. A metallic head with iron jaws filled with razor-sharp teeth. Two iron wings too small to use for flying.
Hephaestus looked at his cute and handsome Drakon Automaton with a warm smile. Sensing this, the automaton glanced up at Hephaestus and let out a weak squeak, its irises glowing like embers. Hephaestus patted its head before picking it up.
"Your name is Sideros, the first living automaton. Drakon of Iron. Welcome to life, my child."
Sideros nuzzled its head against Hephaestus and started to purr, similar to the soft hum of a car engine.
Hephaestus could feel a sudden surge of power go through him but he ignored it as he continued to hold his son.