|Feeder in the depths|
Source: Monster Codex, pg(s). 196
Feeders in the depths begin life as ordinary sharks, raised by sahuagin priestesses and fed the flesh of intelligent aquatic humanoids. As the shark eats, a priestess chants blasphemous rituals that infuse it with malign power and stolen intelligence until it transforms into a feeder in the depths after thirteen midwinters.
Feeders in the depths lose the ability to communicate with other sharks and feel no kinship to them. They view themselves as equal partners to sahuagin, and are loyal as long as they are respected and allowed to hunt; otherwise, they will rip apart their 'masters' and escape. Feeders in the depths do not breed true, giving birth only to normal sharks or monstrosities, never to young feeders in the depths.