Run Yu / Night Deity
Fictional Character
The first and eldest son of the Heavenly Emperor of the Celestial Realm and a Dragon Fish Princess of Dongting Lake, Run Yu is an immortal with water essence. He is the god in charge of the night and only has the nightmare beasts as company. He has to keep a relatively low profile and a reclusive life in the Celestial Realm as the Heavenly Empress is constantly wary and suspicious of him because she fears that he would one day usurp her son, Xu Feng's, place as heir to the throne of the Celestial Realm. Despite the Heavenly Empress's cold detachment towards him, Run Yu maintains a good brotherly relationship with Xu Feng (to Xu Feng's mother's dismay).
This whole dynamic slowly begins to change when he meets Jin Mi.
(Source: MusicalVeggies at MyDramaList)