Remoras are responsible for carrying dreams from shark to shark. Their hosts lack the creativity required to produce dreams independently, as their cravings for blood drown out anything resembling an imagination. For them, the unreal is nothing more than a distraction that cannot be killed and digested.
Even so, evolution has not rid them of their biological need for dreams, and they thus depend on remoras to bring them their prescription. These opportunistic fish fasten themselves against the sharks’ cartilaginous skin, into which they inject a black serum called remorin. This fluid contains clusters of loosely-associated pseudonerves which store all the memories and information required for the couriered dreams to take place. Electrical activity in the brain activates these false dendrites, causing them to behave as though they were natural extensions of the already existing nervous system.
These dreams are occasionally experienced by human thrill-seekers, who inject themselves with remorin to experience the thoughts of another species intravenously. The pseudonerves carried within the serum are able to interact with the human nervous system, but only under one condition: that the body of the dreamer is fully submerged in seawater. Without the requisite oceanic pressure, pseudonerves disintegrate in human blood, preventing any pharmacological effects from manifesting. Divers who undergo this process are advised to bring at least one spotter with them, to ensure that they sleep safely, and don’t do anything rash upon awakening.
Those who have experienced these dreams first-hand describe feeling what it is to be both a shark and a human simultaneously. Though they have gray, leathery skin while unconscious, they know this texture from the way it feels against fingers that they don’t seem to actually have. Though their gills tend to be a reliable source of respiration, the anxiety caused by a slowly-depleting oxygen supply remains. Most alien of all to human dreamers, however, is the hunger that manifests. Experiencing a shark’s blood sense for the first time tends to be terrifying, as most modern humans have never felt the need to kill.
The dreams that these intrepid divers experience are filled with prey that cannot be found in any modern ocean; in fact, the few creatures within that have been successfully identified have been extinct for hundreds of millions of years. For this reason, some paleontologists speculate that the same dreams have been passed down from a single, common ancestor: the last of their kind to wonder and imagine.
Dolphins, on the other hand, have complex and creative dreams.
One diver claims to have dreamed of being swallowed by an ancestor of Charybdis.
There are tesseractive sharks out there, too, who can sense future blood.