Sun is a student at Haven Academy.
Sun has a low opinion of the organization, regarding its members as "Stupid holier-than-thou creeps" for the extreme methods they use to achieve their goals. He encountered the group twice after meeting Blake Belladonna: the first in a fight coming to her aid, the second going undercover with her to a meeting as a potential new recruit. He likely later fought against them during the Battle of Beacon, in addition to battling Grimm, AK-200s, and Paladins.
Neptune is an old friend of Sun and a member of his team. The pair share a close bond of familiarity and tease each other in a good-natured fashion. Sun seems to dislike it when Neptune acts like a "nerd", as seen in the library when Neptune said libraries are meant for reading. Sun seems to have a close relationship with Neptune as he was the main member in the team to coax Neptune to overcome his hydrophobia and help Team SSSN win against Team NDGO.
Although interactions between the two have been few, Sun seems to get along well with Ruby. Sun seems willing to help Ruby and her team in their investigation with the White Fang, telling her that friends should always be involved in each other's plans.
In "Battle of Beacon", Sun is willing to let Ruby borrow his scroll to summon her weapon after her scroll was destroyed by Mercury. Later, in "End of the Beginning," Sun tells her that she'd better come back after she and Weiss return to Beacon Tower to save Pyrrha and Jaune.
Although unaware of it, Sun Wukong is seen as "riff-raff" by Weiss, who has prejudices against Faunus due to her family's history with the White Fang.
Despite her lack of trust, Weiss appears somewhat grateful towards Sun for helping Blake when she runs away; although, she says that she's "still not quite sure" how she feels about him.
In the Beacon Academy library, Sun refers to Weiss as "Ice Queen," implying he holds a negative view of her personality. Sun seems to be oblivious of Weiss' annoyance to him casually hanging in front of Team RWBY's dorm room window in "A Minor Hiccup" just after the girls were finished changing clothes; at Weiss' inquiry to what he means "he does that all the time", he clarifies that he climbs trees all the time, which only annoys Weiss even more.
In "Battle of Beacon" Sun expresses concern for Weiss when she runs off with Ruby to save Pyrrha and Jaune, telling her that they better be back. This shows that he cares for her to some extent.
Sun Wukong developed an attraction to Blake when he first saw her. In addition, he suspected Blake was hiding something under her bow.
Sun was the one who comforted Blake after she fled from her teammates, and they quickly formed a friendship. Although his petty law-breaking annoys Blake, she earlier sprung to his defense when Weiss was speaking ill of Sun.
At the same time, Blake's quiet and reserved demeanor causes Sun to tease her a little. Even right after they first meet, Sun seems to be somewhat protective of her, shown when he jumps in to help her during her fight with Roman Torchwick. Both seem to work together well during the following fight.
Sun continues to pair up with Blake during her investigation into the activities of the White Fang. Later, he nervously invites her to the dance only to be shut down by an unstable Blake. This clearly hits him hard, as he appears to be rather downcast afterwards.
After Blake is convinced by Yang to ease up on the investigation, she makes up with Sun, and they go to the dance together. The two are later seen dancing and smiling, indicating that Sun's attraction towards Blake may be mutual, further evidenced by how he talks about her with Neptune.
In "New Challengers...", Sun points and winks at Blake in the audience while he and Neptune are celebrating their team's victory in the match against Team NDGO, and Blake blushes in response.
Later, in "End of the Beginning", Sun saw Blake run away, offscreen, after they had reached Vale.
In "Of Runaways and Stowaways", it is revealed that Sun has been following Blake after the Fall of Beacon instead of returning with his team to Mistral. Sun reveals himself to help Blake and the ship's crew defeat a Sea Dragon, but Blake is irritated that Sun has been following her for months. Sun explains that he believed Blake was going to take an offensive against the White Fang and wanted to help her. When he discovers the truth that she instead wants to sort out her own personal issues, he is still willing to accompany her as she travels home to Menagerie, stating that Grimm are getting more dangerous and the White Fang may still pursue her even if she tries to stay out of its way.
In "A Much Needed Talk", Sun and Blake's relationship becomes strained after he tries to warn her about the White Fang. Despite it, Sun is still willing to go after her when she chases after a spy.
In "Taking Control", after waking up from being unconscious, he tells Blake that he would do it all over again to protect her and that shutting out the people who care about her enough to fight by her side only hurts them more.
Despite only being shown having a few interactions, Sun also seems to get along well with Yang as well.
During "End of the Beginning", Sun looks after an injured Yang and Blake at Ruby's request. Later in the episode, it is implied that Sun personally told Yang that Blake left.
At first, Sun tries to make a good first expression on Blake's parents. Although he manages to win over Blake's mother, he does not manage to impress her father, as Ghira bluntly tells Sun he really does not like him multiple times. Sun is thoroughly intimidated by the man.