Yuan-Ti Purebloods are serpent creatures left over from an ancient, decadent Human Kingdom. Centuries ago, their dark gods taught them profane, cannibalistic rituals to mix their flesh with that of serpents, spawning a society of hybrids in which the most serpentine are the leaders and the most human are spies and agents in foreign lands.
Purebloods mature at the same rate as humans and have lifespans similar in length to theirs.