Poseidon

Poseidon is a fearsome, haughty, and cold-hearted individual, shown when he mercilessly killed his older brother, Adamas.[2]

Like many other Gods, Poseidon despised Humanity and considered them nothing but filth. Poseidon is also a very taciturn and arrogant individual, viewing himself as perfect, saying that he doesn't need any supporters, even calling other Gods "useless bottom feeders" after glaring at them,[3][4] insulting his older brother and later Kojiro Sasaki,[5] even bitterly cursing him with his last breath as he died.[6]

Poseidon disdain
Poseidon's disdainful look.

His personality is what Hades believes makes Poseidon the person most worthy of the title of "King" more than any other God, even more than himself. Despite his cold exterior, Poseidon does possess some emotion, especially when it comes to his brothers. Though he dealt him a fatal wound, Poseidon chose to let Adamas live and didn't mind when he was healed by Beelzebub and continued living under a different name in Helheim.

Poseidon calls Hades brother
Poseidon tells Hades that he will not thank him, however calling him "brother"

Poseidon also seems to care for his eldest brother, Hades; after witnessing Hades defeat the Titans by himself in order to protect his younger siblings, Poseidon uncharacteristically smiled and called Hades "Brother", which he'd never done before. Even before seeing this, Poseidon expressed worry for Hades when he heard his brother went down to Helheim alone to deal with the Titans. This love also extends to Adamas, choosing only to cut him in half and letting Hades and Hermes retrived the injured god for surgery.

Poseidon takes the form of a tall and muscular man, his face usually completely apathetic and devoid of any emotion, with golden-blonde hair as well as light blue irises and black pupils. He donned an ornamental patterned golden choker and dark blue clothing with a golden border that covers the entire upper half of his body, revealing his abdomen and chest. Around his biceps, he wore a pair of golden rings.

Poseidon wore a pair of seaweed-colored fingerless gloves, with a blue band on his wrists, whilst around his waist was a white coat with golden circular patterns, one which split in two at the front with a single cloth going down like a loincloth.

Additionally, beneath the coat were a pair of baggy pants that matched the cloth on his arms, tucked into a pair of seaweed-colored boots with designs similar to those of ancient ruins in the ocean depths. He was always seen carrying around his primary weapon, a highly stylized trident as long as his body.