In ancient Greek mythology, what was the relationship between Nyx and Erebus?

Nyx was the personification of night in Greek mythology. Nyx played an important role in myth as one of the first divine beings to come into creation. In the Theogony of Hesiod, it is stated that Nyx was the daughter of Chaos, which makes her one of the first creatures to emerge from the void. This means that Nyx was sister to some of the old deities in Greek myth, including Erebus (Darkness), Gaia (the Earth), and Tartarus (the Underworld). From these primeval powers came the rest of the Greek gods and goddesses. Nyx was also responsible for bearing her share of divine children. She gave birth to Eris (Discord), the Moirai (the Fates), Hypnos (Sleep), Nemesis (Retribution), Thanatos (Death), and the Hesperides. While these beings were born from the goddess alone, without a father, Nyx also had children by the god Erebus, to whom she bore Aether (Air) and Hemera (Day).