Nyx Thanatos. 

With her parents being a God and Goddess; Nyx was bound to end up with some kind of power.

The moment that Persephone returned to Olympus after her daughter's birth, it was revealed to her that the Primordial Goddess Nyx had faded but her powers and domain over Goddess of the Night had not faded but had, instead, temporarily passed to Erebus to hold onto until the true Goddess was available to take the reigns, which was revealed to be the newborn Thanatos

But with the power came the responsibility of keeping the balance between night and day and the moment that the young woman entered Auradon, the magic settled within her and she had to attempt to keep her temper so that her cousins did not think her a threat to their realms (Artemis and Apollo).

 Verses 

Isle of the Lost: When Hades was banished to the Isle he was separated from his firstborn daughter and left with his eldest son; then he had Nyx who he tried to keep protected along with his youngest children. Nyx is strong-willed and will do anything to make her family proud.

Auradon: After the Core Four were taken from the Isle, the King, and Queen deemed it safe enough to slowly allow more children across the sea and into their schools; now it’s Nyx’s turn and there will be hell to pay for whoever crosses her.