Famed in heraldry, hippocampi are the steeds of the sea. Most encounters with them will therefore usually be encounters with their riders as well.
Good-hearted does not equal welcoming. The key to winning an audience with a triton tribune is to participate in the annual roundup of the wild hippocampus mustangs off the Plymouth Shelf.
Polar hippocampi can be quite loyal. The Inu tribes of the North are human, not even gillmen, yet as soon as the pack ice melts their hippocampi steeds return to take them hunting, bearing their harpoon-wielding riders safely above the frigid arctic waters.
The rare giant hippocampi often have adaptations appropriate to the darker depths in which they dwell—bioluminescent orbs, razor-sharp, spines, expandable jaws, and so forth. Most are wild, and those few that have been domesticated are the property of ceratioidi crime families, who jealously guard the secrets of their breeding.
—Pathfinder Bestiary 2 155