Encounter wih a graceful Shadow Elf

Shadow elves are not visible in daylight, but also not at night. They move in the shadows and scurry with them quickly and skillfully very quietly, so that no gaze meets them. Catching an elf is almost impossible, but their curiosity sometimes causes them to leave the protection of darkness to cautiously approach humans and observe them, for study purposes of course, in their nocturnal pursuits. Unintentional encounters cannot always be prevented, even with all caution. What is left behind are people who are immediately put to sleep by the fairy dust and forget the memories of the unusual encounter. It also seems to work very reliably, because for centuries there are no records of stories in which elves or fairies are reported.