In Japanese, a radical is a smaller piece of a kanji. Many radicals are their own kanji with its own specific meaning, and then when combined with other radicals adds or changes the meaning of the overall kanji. For example, ? meaning "tree" becomes a radical in ??which means forest. So that's what Koe is referring to on the symbol on his aunt's back. It's a piece of the rune that means "love" which is made up of the two radicals of "promise" and "time".

When I first designed Fairy's I wanted them to have cool geometric tattoos. And the colors of those tattoos would likely be related to their family, most dominate colors being primary colors of red, blue, and yellow. Also, to go along with tattoos they would dye parts of their wings different colors, so the designs would occasionally change as feathers grow out.

Anyways, there's some Eldair lore for you today! I hope you have a nice peaceful Sunday!