Neptune is a student at Haven Academy.
Neptune is a member of Team SSSN.
Neptune has a close friendship with his teammate Sun, who introduces him as his "old friend". Sun trusts him enough to confide secrets with Neptune, even though Neptune may not always be the most reliable at keeping them. They often tease each other good-naturally, with Sun calling Neptune a "nerd", though Neptune prefers the term "intellectual".
Sun is also familiar with Neptune's crippling fear of water. When Neptune flees the ocean battlefield during the match against Team NDGO in "New Challengers...", it is Sun who continuously tries to coax him into participating in the battle. After a great deal of frustration, Sun is eventually successful in getting him to help win the match.
In Chapter 11 of RWBY: The Official Manga, he comes to Sun's side and successfully block Roman's attack before he can kill him.
Scarlet is Neptune's teammate on Team SSSN. According to Sun, Neptune has a tendency to gossip and share secrets with Scarlet. In "New Challengers...", when Scarlet worries about getting sand in his shoes during in their match against NDGO, Neptune makes a point to remind Scarlet to "be cool".
Sage is Neptune's teammate on Team SSSN. When Neptune flees from the watery half of the battlefield in their match against NDGO, Sage incredulously asks him what he is doing.
Neptune appears to take an interest in Weiss. He uses the same line as Jaune Arc, calling her "Snow Angel", but he has exponentially more success. When Team RWBY finishes planning their investigation, Neptune also seems to want to work with Weiss; he is constantly smiling at her.
Despite Weiss herself inviting Neptune to the dance, he refuses because he does not know how to dance and is embarrassed by that fact. He later approaches her after receiving Jaune's encouragement, explaining his initial refusal to Weiss. At the actual dance, Neptune admits that he likes Weiss even though he does not know her very well.
However, in "New Challengers...", either unaware of Weiss' presence or in spite of it, Neptune attempts to flirt with the girls of Team NDGO. This greatly angers Weiss, who begins cheering for the other team, exhorting them to "break his stupid face". Weiss and Neptune have yet to have any meaningful interactions since.
In the RWBY: The Official Manga, his first meeting with Weiss is different than the show, he instead asks her if she's the Snow Angel of rumor and how it's enchantingly gorgeous title which makes Weiss blush.
Still, while working as partners for a brief period of time, they cooperate well enough to attempt to slow down the Atlesian Paladin-290. However, Neptune also compliments Yang, remarking "what a woman". Yang either ignores or does not take note of this.
Neptune officially introduces himself to Jaune during the Beacon Dance. Jaune is initially hostile because of his unrequited attraction to Weiss and his belief that Neptune doesn't respect her. However, despite barely knowing each other, Neptune confesses to Jaune that his "cool guy" attitude is a facade and that he does not know how to dance.
After being asked to keep it a secret, Jaune encourages Neptune to approach Weiss and be honest with her instead of trying to act cool all the time. Neptune happily accepts his advice, telling Jaune that he is a really cool guy. Later, after asking Weiss to dance, he tells her that Jaune is the reason he changed his mind, and he mentions that she has a good friend looking out for her.
Neptune and his team remain on friendly terms with Team CFVY. After the Battle of Beacon, the two teams reconnected in the settlement of Coquina, where Neptune's team caught his peers up on what had occurred at the Battle of Haven.
In the epilogue of RWBY: After the Fall, Neptune attempts to flirt with Coco, but she does not reciprocate his attempts.
In RWBY: After the Fall, Neptune attempts to flirt with Glynda, but Glynda does not reciprocate his feelings.
Neptune briefly fought with Roman once. In "Painting the Town...", while riding with Yang on her motorcycle, Neptune approached Roman inside an Atlesian Paladin-290. He and Yang had to evade vehicles knocked back toward them by Roman. Neptune fired his gun at the Paladin, striking it with three out of four shots. He then transformed his weapon from a gun into a trident and leaped on top of the Paladin, striking it. Roman spun enough to dislodge Neptune, incidentally knocking Neptune into Sun and removing them both from the fight.
Neptune met Junior when he accompanied Yang to Junior's Club to discover Roman Torchwick's whereabouts. The two did not hit it off in any way; Junior even suggested that Neptune is stupid.
Neptune attempts to flirt with Ilia at the Mistral station without realizing she is not interested in guys.