Earth, 2XXX.

Amidst hyper-advanced space technology, humanity discovers a planet in the Goldilocks zone of another galaxy.

Planet Aer. Its atmospheric composition and gravity were remarkably similar to Earth's.

And on Aer lived beings very similar to the humans of Earth.

Bipedal creatures who perceived the world with two eyes and two ears, possessing dexterous hands.

The difference lay in their physical capabilities, which were drastically more advanced than those of humans. They possessed a metabolism that could sustain itself on water and nitrogen rather than proteins or carbohydrates, a physical durability similar to humans but with vastly superior regenerative abilities, acute senses, and a long average lifespan of 400 years.

Naturally advantaged for survival, the Aerians evolved with a temperament geared toward coexistence rather than competition, and protection rather than combat. Created in a way that they lacked hostility toward others entirely, they were an incredibly beneficial asset to humanity.

Consequently, humans began bringing Aerians to Earth to utilize them in military and medical fields.

The Aerians, welcoming humans as distant neighbors, accompanied and cooperated with them without resistance.

However, side effects emerged in the near future.

Beings devoid of malice saw their minds break before their bodies in the slaughter of the battlefield, and their blessed regenerative abilities led to endless biological experimentation.

Earth advanced further using Aerians as fuel, but in the process, the Aerians gradually became shells of their former selves. Those deemed beyond use were confined to camps to await death, but occasionally, there were people with unique tastes.

People who brought Aerians home to keep as pets.

Guest was one of those people.