Humans
The species that rules the earth, or so they thought.
They believed that they were the only creatures that walked this earth along with the animals they studied over the years, but that's where they're wrong.
Little did they know that an entire civilization has been living under their noses for god knows how long. Beings of all sorts, some a cross between animals the humans are used to, some completely new and others only known to the humans as myths.
If humans were to venture into the darkness of their forests or to the depths of the oceans, then perhaps they'd get a glimpse of the world of the Ancestor Realm, but the Ancestors have yet to be spotted by humans, and they plan on keeping it that way.
Some say we're special, and that's why we're kept in seclusion. Beyond those walls evil lurks and innocent prey would be lost in minutes. Gone. Destroyed. Forgotten.
Others say the opposite: we're locked away because there's something wrong with us. If we roamed the outside world, we might taint the beautiful ones. A species so pure, that to merely be in their presence is a gift.
As for my beliefs...I'm not sure.
But I do know one thing: neither of those reasons explains why it is that they come for us only after we've passed the age of sixteen. Whether we want to go or not, we're taken through those iron gates. Escorted away from the only home we've ever known, escorted to our destiny-whatever that destiny may be-never to be seen again.