The Earth is split into two dolphin-centric, high-tech timelines where mankind vanished; one is populated by superstitious former slaves, and the other by the militaristic and xenophobic Clan.
Type: BlossomIn this reality, dolphins were made weak and gullible. Mankind enslaved them and exploited them to operate underwater mining machinery. As individuals, the dolphins of Man's Nightmare are slow and stupid by modern comparisons. They can articulate and communicate well, but they have trouble understanding abstracts and causal relationships, and they're easily confused by too much complexity.
Man bred the dolphins into three castes, each suited to their work. The perceptive Cimson with red-dyed flippers would supervise works and troubleshoot problems, keeping production running smoothly. The ghost-pale Circle operated the machinery that poisond the very waters around them, often horribly scarred by the chemicals they were in proximity to. The orange countershaded Movers were the muscle, part-orca and more belligerent than their cousins.
The caste dolphins generally understand that offworld visitors are not "their" mankind, and await the return of their masters with the same patience they'd shown in centuries past, maintaining projects and works for no reason at all, blind and deaf to the possibility that their masters are gone forever.
The cetacean societies in Dolphin's Nightmare are wondrous cities made of coral and shell that has been engineered into specific structures, with doors and locks and facilities made with biotech. It looks pretty, but the society thatbuilt it is rtten.
Those cetacean societies found in Dolphin's Nightmare are smarter, but they don't have anything governing those smarts. The Clan has been twisted into a society made aggressive, xenophobic, and intensely selfish. It's every dolphin for himself. It doesn't help that their leadership is so militaristic and ready to fight, crush, and reject that which they don't understand, viewing compassion and kindness as weaknesses to be purged. What relationships they do have with the outside worlds are cold, calculating, and exploitive.
Societal status is determined by a series of rank marks, located on the sides or flanks. The higher-ranking Clan members also tend to have more drastic modification of their body, usually through cybernetic grafts.
Both realities inhabit the same metaphysical space, making each equally viable. One can visit each timeline separately from the World Tree, or even cross between the two via the local vine network.
The dolphins of Man's Nightmare are complacent. They have little ambition, and are too passive to explore far beyond their polluted waters. In most cases they aren't too curious about visitors and won't react much unless attacked, in which case, they'll fight back.
More aggressive are the Clan of Dolphin's Nightmare. They have no qualms about exploiting others, and will bully and torment even offworlders when bored. Humanity is an inferior species to them, and they suffer offworlders' presence only grudgingly. They will make alliances of convenience, but only when it benefits them. The small pod of Outcast welcome strangers; they're not truly selfless, but they also aren't aggressive or malicious, either.
Both Earth's populations interact with one another on occasion. The dull and superstitious castes look on the Clan with awestruck horror, willing to either flee or attack them on sight. The Clan are disgusted by their dim-witted cousins, tormenting them if they accidentally stray into Clan waters, and occasionally raiding Man's Nightmare for slaves.