This hatchling appears to be... dead?

Perhaps not. It seems to be active during the night.

Young dragons are relatively defenseless. They are born with relatively soft scales, which are shed and replaced with harder ones as the hatchling matures. Once a hatchling’s wings grow in, it typically marks the beginning of maturation. At this point they are often capable of hunting on their own and are usually left alone by their mother.

Datai's name means "miscarriage" or "abortion."  Through a cruel twist of fate, Oketsu the vampire gained access to the egg laid by Sekiun and sired by Ukedaichi, slipping in under the cover of darkness while the usual cave guardians were disoriented by a lunar eclipse.  When Sekiun discovered the tainted egg, she was so distraught that she could not bring herself to destroy it.  Instead, she rolled the egg down from the mouth of the cave and into the forest, hoping it would shatter in the descent.  It did not.  It was later recovered by Anoyo and Oketsu, and the hatchling was claimed to be their own.  Datai is a proper vampire dragon, vicious, conniving, contrary and always hungry.