Nidhogg had two divine duties, despair and black dragon.
Among them, "despair" was the primary duty, with the potential for medium divine power, while "black dragon" was the secondary duty, with the potential for weak divine power.
The duty of "despair" was also extracted by Eve and sealed within her Divine Country.
A divine duty was not something that could be casually devoured. It was rather useless for her, but throwing it away or destroying it would be a waste, and supporting a sub-god would be risky, so Eve simply sealed it for later use.
As for "black dragon," Eve intended to reserve it for Mairrel, turning her into a sub-god.
Although "black dragon" was merely a duty with weak divine power potential, it was a perfect match for Mairrel.
In the Ancient Era, a dragon god possessing a specific dragon species' duty was called Dragon King by other dragons, and the Platinum Dragon King possessed the "silver dragon" duty.
