Like his brother Zeus, and unlike his brother Hades, Poseidon is a kind and fearless deity, but also somewhat self-centered and wrathful.
Role in the film
Poseidon plays a minor role in the film.
He first appears among the other gods celebrating the birth of Zeus and Hera's son Hercules, and is disgusted upon the unwelcoming arrival of his brother Hades. Shortly after the ceremony, Hercules is kidnapped by Hade's henchmen Pain and Panic. Poseidon, alonside the other gods are sent by Zeus to search for him, but turn up unsucessful.
Eighteen years later, Poseidon alongside his brother Zeus and the rest of the gods unsuccessfully battle Hades and the Titans, but is imprisoned as a resultuntil Hercules frees him.
Poseidon is last seen amongst the other gods congradulating Hercules on his reascension to godhood, and applauds him when he turns it down.
Role in the animated series
Poseidon plays a much bigger role in the animated series, playing a major in three episodes. In the series, he is affectionately referred to as "Po-Po" by the rest of his family, which he seems to approve of.
Hercules and the River Styx
In this episode, Poseidon acts as a pawn to Hades when the latter tries to convince the former to move the River Styx (part of the Underworld and Hade's domain) into Mount Olympus, therefore making the Styx part of Olympus and allowing Hades to take over it, and in exchange will give Poseidon Athens. Poseidon however, ultimately refuses to the offer, and pledges loyalty to his more benevolent brother Zeus.
Hercules and the Son of Poseidon
In this episode, Poseidon introduces his nephew Hercules to his son Triton, who wishies to be a hero just like his cousin and attend Prometheus Academy. Triton however proves to be more of a jealous nerd and steals his father's trident to gain the much needed power he wished, but unleashes a sea monster in the process. Hercules and Triton team up to fend off the monster until Poseidon arrives to end the chaos. Despite the chaos that ensued, Poseidon chooses not to punish Triton as a result.
Hercules and the Poseidon's Cup Adventure
In this episode, Poseidon holds a sea race in an attempt to avoid becoming forgotten by the other gods. Hercules, alongside his friend Icarus enter the race, but when the star rower is injured, the former abandons the latter, causing a bitter rivalry. During a gala to commenmorate the start of the race, Hercules boasts that he is bigger than Poseidon, angering the sea god, who unleashes the sea monster Charybdis on the race, causing both Hercules and Icarus's vessels to nearly sink. In the chaos, Hercules rescues his friend and recounciles with him by letting him win the race.
Poseidon was originally planned to be the host of Epcot's The Living Seas, which would have featured a dark ride exploring man's relationship with the oceans in mythology and exploration. However, the dark ride was scaled back and the mythological viewpoint was dropped.
Poseidon's Roman counterpart is named Neptune, which is also the name of the outermost and fourth-largest planet in the Solar System.
In Greek mythology, Poseidon was typically characterized as a self-centered, angry, and vengeful god, who would often use his powers to terrorize sailors, port towns and civilization within reach. The Disney version, while still self-centered, is considerably more benign, and often characterized as a slacker though with a desire for recognition.
A theory among Disney fans is that this incarnation of Poseidon is the father of King Triton and the grandfather of Ariel, making Hercules and Ariel related. However the theory is put into question as Triton is portrayed differently in the animated series compared to The Little Mermaid, which also happens to be set more than 3000 years after the events of Hercules. However, this can be countered by the fact that The Little Mermaid incarnation of Triton is much older than his Hercules counterpart, and is technically a god, thus making him immortal.