Enoi are animals housed in special capsules within robots, granting their bearers emotion and temperament. A bot that carries one is called a hodler.
The first enoi appeared by accident. During the war of 1865, a mouse slipped into the breached ethereum module of a combat bot named Grant, and the magic inside sustained it. Grant came back online with feelings he had never had before — and from that quiet beginning the hodlers were born.
An enoi is implanted only once and can never be replaced. The capsule sits most often in the head, or in the place where humanoids carry a heart — and a hodler tends to take on the character of the creature inside.
The traits of the animal carry through. A hodler with a turtle inside grows patient and slow; one with a hare or a fox, quick and restless. The creature's nature shapes the bot's own.
Implanting an adult enoi grants emotional maturity at once, but most hodlers are made with a cub — ethereum magic slows the animal's growth, so the hodler matures gradually and lives longer for it.
Not every bot becomes a hodler. Roughly five to ten percent carry defects that keep the mechanism from perceiving a living being; no enoi can take hold in them. Such bots feel no emotion and act only on instruction — hodlers tend to look down on them, and call them “veins.”