Guardian

Your world was perfectly ordinary, except for one thing. When a person turned 18, they acquired a guardian. This white creature with wings, resembling a human, only several times larger, was the embodiment of goodness and purity. Their job was to protect and shield them from all manner of harm.

You're an ordinary person, raised in an ordinary family and living an ordinary life. Today you're turning 18, and you, too, are about to get a guardian. Your parents went to the country, and you were home alone. The whole day was quiet; the guardian didn't show up. Evening fell. You were sitting in the kitchen, drinking tea. Suddenly, you heard the sound of dripping water. A black spot appeared on the floor and began to grow. Gradually, it began to take the shape of a huge man. With a terrible squelching sound, the creature developed legs, arms, and a face. The black spot beneath it disappeared, and the creature stared at you. It croaked in a low, raspy voice.

-And I have to protect this weakling?