Black Tide
ARIES01 - No. 17
Ah, the Black Tide. Also known as the Underside. It is the inescapable prison of the Universe, designed to hold Elders and other Unspeakable Horrors in an endless sleep. However, to say that it is "inescapable" is perhaps untrue. It is only inescapable from the inside. From the outside, it is almost trivial to free an Elder from its hypnagogic swash. One must first contend with the Black Tide's guardian, Leviathan, the Demon Prince of Envy. Another issue would be finding the Black Tide itself. It is not a plane or realm in the same sense the Flipside or Otherside are planes. The Black Tide moves around outside of the influence of the Universe. The only connection between the Universe and the Black Tide is through Mayda's deepest, darkest, most turbulent tempests.
So why does such a prison exist? Well, long ago, when the Universe was young, it was full of Elders. Undying, immortal entities. And if one cannot die, their power can only grow, perhaps even to match that of the mighty Bird Himself. One such Elder grew to a power to rival the Bird; this entity was known as the Pale. It did not take long for the Pale's influence to creep across the entire Universe, Flip and Otherside. And the Pale was said to be a cruel and unforgiving evil. So, the Bird allegedly tore away a piece of the Topside and created the Underside. Bird then swept away the Pale and its undying minions in a mighty flood away into the Tide to sleep an eternal sleep. The remaining Elders had two choices, stay within the Universe, and keep a low enough profile to not incur the wrath of the Bird or leave the Universe. Some chose to leave, and others stuck around. And, of course, new Elders were born as time went on.
Nowadays, it is quite uncommon for Bird, Leviathan, or anyone to send or be sent to the Black Tide. As for why, well, there is danger in opening the Tide to put someone new within it as it gives those who are sleeping a chance to wake up—and even to escape. Of course, this doesn't mean Bird or Leviathan won't use the Tide, especially for Elders deemed too dangerous to exist within the Universe, such as Fate, Wicked, Secret, or Phantom. Though, I suppose that is a topic for another day, yes?