Autochthon and Souls
The 2nd edition Exalted Autochthonians supplement says that Autochthon cannot make new po souls, and that he eats them, and that this is the source of stillbirths in Autochthonian human society. This answer seems odd to me, because it would also suggest that there can never be the swarms of vermin within Autochthon that have been described in the source material. Being without a hun soul doesn't necessarily cause instant death, either. Perhaps a newborn needs a hun soul to kickstart its Essence.
To be clear, you can count me as among the camp which believed that the po soul, or the animal soul, was indeed the same as the soul which is born by animals. Humans, and other higher beings, would therefore be marked by their possession of a hun soul, in addition to their animal soul. Thus, a dog would only possess a po soul, while a human being would possess a hun soul and a po soul.
An Exalt would possess a po soul, a hun soul, and an Exalted essence.
For Dragon Kings, this might suggest that they begin life with a hun soul held in remission state, dominated by their po soul. As they grow into Dragon King enlightenment, the hun soul would take control and the po soul would receed to the state where it lies for other sentient mortals.