From Sonic Retro
Black Narcissus tends to be the brains of the Metarex. He is also obsessed with his appearance and likes to look at his reflection. He seems to be more effeminate than the other members of the Metarex.
In episode 67, he sets a trap for Sonic by first luring Cosmo, and then Chris, onto the Metarex's ship. Sonic becomes angry at him for scaring Cosmo and injuring Chris. With the fake Chaos Emeralds all over the room, Sonic transforms into "Dark Super Sonic". Black Narcissus becomes somewhat amused by this.
In the same episode, Dr. Eggman somehow gets on the ship. When Black Narcissus attempts to attack him, he is restrained by Decoe and Bocoe and then attacked by Bokkun. His armor becomes severely damaged. Because of this attack, he shows a strong dislike for Dr. Eggman, even when he decides to "join forces" with the Metarex.
In the final episodes, Black Narcissus assists Pale Bay Leaf in trying to destroy the Blue Typhoon, but to no avail. He, Pale Bay Leaf, and Dark Oak then merge their bodies together in their final attempt to take over the universe. He is eventually destroyed along with Dark Oak, Pale Bay Leaf and Cosmo by the Sonic Driver.
Narcissus in Greek mythology
Black Narcissus' name may have been also inspired by the Narcissus of Greek mythology. Narcissus was a man who was punished by the Greek gods which resulted in him becoming obsessed with his reflection, much like Black Narcissus is. His story also led to the creation of the word narcissus; a love for oneself. The Narcissus flower was also named after Narcissus.