Dark Pact
The strange alien monstrosities found in the dark mountains of the Obsidian Peaks often have unexplainable behavior. What's more curious is how such vastly different creatures could remain in such close proximity with each other despite their competition for resources and space and why they rarely, if ever, leave the mountain range except to go deeper into the lands of Hollow Earth. One theory scholars of the aberrations have posited is that they all seem to have some dark pact with each other. A sophisticated schedule or territorial map which keeps them from interfering with each other while they continue to parasitic and predatory behavior on all non-aberrations. This has never been confirmed, as most aberrations seem to have no desire to even communicate with mortals, but it is the current theory.