The Dark Kind came to the world as conquerors. They failed. Now they are odd neighbors.
HeartKind bands are a way for Dark Kind (or any Deamonic/Monsterous kind) to show that people have nothing to fear from them.
As part of The Pact that ended the Six Stars Demon Wars, various places were given over to the Dark Kind. This is their neighborhood in the city.
In cultures and langauges with very few acceptable personal and family names, nicknames will be used. These nicknames will be based on their physical traits and personalities. So instead of five Ryon Khans, you have Big Ryon, Little Ryon, Fast Ryon, Ryon the Priest, and Ryon with coin. It will make finding people, for an outsider, difficult.