It runs in the family to be able to see them, communicate with them. Not everyone has one, not everyone needs one, most people can go their whole lives without ever knowing about them, but they're there.
My mom kind of helped hatch a bunch of them, and maybe because of that, maybe just because, but I can talk to them, speak their language, it's all emotional tags mostly, and sounds.
Anyway, the tattoos, about a month and a half back I was taking a shortcut through the Shadows' dimension to get home from London, and mis-calculated and ended up in the ocean. I got hauled out again by a couple of islanders, and they took me to their island. Apparently every few years somebody comes along as sort of a Herald to a fresh wave of Shadows, these people know the Shadows, can understand them, a few can even speak the language. I was the herald this time, because of Kitten, my Shadow.