Trash Queen adamantly refuses to answer any asks regarding Aoandon, so I'm going to you. Did they brutally murder people after a string of ghost stories?
Aoandon. Light 100 blue lanterns and tell a scary story. At the end of each story, blow a candle out. Each story is scarier than the last. Until finally, in the dim light of the last candle, you weave a tale of pure terror and blow the last candle out. Smoke rises and darkness falls. Out of the shadows a figure born from fear dressed in a white kimono with long dark hair and pointed black teeth grins at you.
Aoandon are not monsters in the traditional sense (Toriel, Sans, Hapsta, etc), but creatures of the void summoned by heightened human emotions[fear]. The lantern ritual blurs the lines between this world and the void, allowing them to enter if the ritual is completed. They are mainly curious. But sometimes mischievous and nasty. They like the taste of fear and creating more fear. They're in it for the thrill, not blood.
They have been known to kill, yes brutally at times. Usually to get a reaction out of others. But they generally prefer just scaring the crap out of people. Because survivors tell ghost stories. Dead people don't.
If they kill, a person's fear flares and then is over. They prefer a long slow stream of fear. Lurking in shadows. The movement in the corner of your eye. A reflection in the mirror down the hall. A grainy image in a photograph.
Those they haunt feel cold, drained and lethargic. Often complaing of mysterious illness. Prone to night terrors and really bad sleep paralysis.
Once summoned, they are hard to get rid of. They don't really die as far as anyone knows, but are repelled by sunlight, happiness and genuine laughter. If a family full of love, light, and laughter moves in to a place they lurk, they will likely leave to find a new haunt or may even return to the void. But as long as the gate is still open, they may find an opportunity to return.
[Side note: I hope I did them justice, I don't know much about them, only what I googled. Hope that's satisfactory, walter]
