Nereus

Prince Nereus is a triton. He is the son of Neptune, the King of the Seas on Andros and of Ligea, Queen of mermaids, and is the brother of Tressa and is the twin brother of Tritannus, who will be the main villain in Season 5. He is also the cousin of Aisha and the nephew of Teredor and Niobe. When his father chose to name him as heir to the throne, his jealous brother Tritannus disrupted the ceremony and was sent to prison.

Season 5
In The Spill, King Neptune was having a ceremony to name Nereus as the next king. But the masked assassin disrupted the ceremony and attacked Nereus. His father later defeated the assassin and found out it was Tritannus. King Neptune sent Tritannus to the prison of Andros. He, his mother, and sister tried in vain to prevent King Neptune from going after Tritannus. When Nereus and his mom went looking for Tritannus, they were turned into mutant tritons like the prison guards. Later in The Eclipse, Aisha de-mutates him and his sister, with the power of his father's sword. in episode 25, he is fatally wounded by Tritannus during a fight. Aisha acts quick to use her only wish to save her cousin, and revive him. Episode 25 ends with Bloom, Flora, the selkies, and himself swimming after Tritannus, who has captured Aisha and swam away with her.

Trivia

 * According to Greek mythology, Nereus is a marine God. He is the son of Pontus, the Sea, and of Gaia, the Earth. He was sometimes called the Old Man of the Sea and with his wife is, Doris, who represented the bounty of the sea and who is an Oceanid nymph, one of the 3000 daughters of the God Oceanus, the World Ocean, and of the Goddess Tethys, the Mother of All Rivers and the Embodiment of all Waters of the World, who are both the children of Gaia and of Uranus, the Sky. With her he had fifty daughters, the nymphs called Nereids, with whom he lived in the Aegean Sea. Among them, Thetis was the mother of the Greek hero Achilles. Another of them is Amphitrite, the wife of Poseidon (the Greek equivalent of the Roman God Neptune), the God of the Sea, and Poseidon and Amphitrite were the parents of the half-man half-fish marine God Triton. There was also another Nereid named Galatea.