Zeus is the Prefect of the Night Class and the judge for prefects final trial. He meets the main character at a party organized for prefects and prefect candidates, and falls for her at first sight. Klaus, a graduated prefect is back at the academy to hide the Devils Whisper, a magical tool containing strong controlling magic, which was actually decided to be confided to the main character, without letting her know about the power of the magical item, disguised as a brooch. Deeper in the Story, Zeus and the main character get together, and Zeus takes the brooch in order to save Lucious, a cursed Prince who, hundreds of years ago, was cursed to wander around a labyrinth with the hope of finally getting together with his beloved Princess, Claudia, with no results, ending up stuck wandering in the labyrinth forever, unaware of the fact that Claudia is long gone. Before finishing his mission though, Zeus talks to Lucious about Claudia, who eventually decides not to destroy the labyrinth, since it's all he has from Claudia. Though, the guard of the labyrinth started destroying it by himself, which ends up in a fight between him and Zeus. In the end, the brooch is returned to Klaus, unfortunately, Lucious is still trapped, and the Main Character and Zeus end up together.
In Hiro Tachibana's route it's learned that Zeus is royalty or quite close to a royal family, although it doesn't specify his title. The MC character starts to understand his behavior due to this fact.
It is also learned that Zeus and Hiro have been together since birth. This is because Zeus and Hiro's ancestors made a journey together and started a relationship of master and servant. This relationship is carried to the successors including Hiro and his father. Despite his royal names neither Zeus nor Zeus' father seem to treat Hiro as a vassal but as a member of their family (kind of like cousins or brothers) which annoys Hiro although he sometimes feels thankful for it.
It is also learned that despite his attitude, Zeus is a person who draws people toward him. They just feel compelled to follow him. This could be due to his royalty blood. Despite his rude and superior attitude he shows care toward people he feels like family or has a certain attraction (Like MC or Klaus), although he tries to hide sometimes. An example is that Hiro says that Zeus has never seen him as a servant but as a family member or when Klaus was cursed Zeus is one of the people who stops by to check on him.
In Lucious Duller' route, it's learned that Zeus' hometown is Queensblade Kingdom. In Hugo's route, this is also shown when at the party that celebrated the "friendship" between Gedonelune and Queensblade, he introduces Liz to General Smith. Liz mentions that this was proof that his family must be quite influential. According to General Smith, he used to be Zeus' teacher at sword fighting and he even mentions that Zeus used to be small and scraggly back when he was his pupil.
Zeus is overconfident about himself. He often says that "[He's] the pinnacle of all creations, alive or dead". He can be rude and tactless due to his overconfidence. In many routes, other characters describe him as full of himself. But deep down he's a nice guy that worries for other people. He also is quite childish since he always gets what he wants, which is a cause of distress on others, especially his best friend Hiro. This is seen in his route when, during Liz second trial: she's asked to choose a partner that could help her pass her trial, and she chooses Klaus to help her. Not knowing his true feelings, he displays a tantrum and Hiro has to ask Liz to talk to him and confess her feelings since Zeus was a child who couldn't figure out and control his emotions, therefore Liz's confession might help to calm him down.
His childish and overconfident attitude always puts him in discord with Klaus, who is the opposite of him. He also lacks the ability to sympathize with other people's feelings, but when he gets the idea he can be supportive. He is very impatient and short-tempered and he doesn't think of the consequences of his actions, such as when he summons dangerous beasts just to impress other people or, like in Hugo's route, when he escapes from prison by blowing up the jail. Everybody was upset that he didn't go for a much quieter method, but he brushed it off saying that they should've told him so before he blew up the gate.
He also likes to tease Hiro a lot. In Hiro's route, he even shares childhood stories that make Hiro embarrassed and even knowing this, he still proceeds to tell the group his anecdotes. In "Dear My Love" spin-off, it's learned that Hiro's past borthdays have been chaotic because he summons dangerous creatures or he tries to prank him. Despite this, MC and Hiro know that despite the awful presents, Zeus' heart is in the right place. He's so childish that every time Caesar is turned into a pig, he laughs out loud, which irritates Caesar.
Most of the times, he can be very rude and have no respect towards any authority. This is shown when he's seen arguing with Klaus, despite that he's a Ministry employee or when he argues with Headmaster Rembrandt and calls him names, though the Dragonkin seems to be able to handle Zeus' attitude and even makes him dig his own grave in some cases, such as when he punishes them at the end of Hiro's normal ending (Zeus had the idea of not letting Hiro carry all the guilt and Rembrandt makes his friends, including Zeus, to help him. Thus Zeus is stuck with Hiro's punishment as well). In Rembrandt's route, Zeus tries to insult him, but he brushes it off with a quick retort, leaving Zeus speechless, which something that amuses to everyone.
Zeus is very good with dark magic since most of the Night Class students rely on this type of magic. He specializes in summoning. He seems to be able to even summon a person from a point to another, like when Zeus was looking for MC, he got tired of the searching and decided to summon her not even knowing that she was at the time in great danger in the labyrinth train. He also seem reckless in his summoning because he often tends to summon dangerous creatures just for the fun of it or because he wants to make an impression or, even worse, because he gets angry. After the summoning he even admits he can't dispel his own magic until the effect wears off and therefore his friends, specially Hiro, tend to deal with the creatures that go from a carnivore human-eating plant or a highly dangerous creature name Vulcanaux.
- It was mentioned in Apple of My Eye that he uses leather shoes.
- In the Spin-off Steaming Love it's mentioned that Zeus is extremely intelligent since in his route, he learns the rules of chess and starts playing with a guy at the Night Cafe, but he loses since he didn't want to sacrifice one of his pawns to make a better move, perceiving the game as a battle field. However, in Hiro's route it is noticed by the MC character that Zeus likes chess and he tends to play with Lucious and winning a lot, which enfuriates the little prince. Also in Alfonse's route when Liz and Alfonse go to visit them at the Night Cafe, he asks Caesar for a match, which he finds discouragingly due to Zeus being a bad loser. Therefore it can be assumed that Zeus only can be good at chess if he's against someone younger or with a mentality keen to his character, that is the one of a child. In Lucious' normal ending, he looks angry because Hiro has won several matches against him. Hiro responds that that's because it was easy to read his movements because he had no strategy. Caesar an Alfonse ask to play too against Zeus, quite sure that he would never beat them, which upsets him.
- According to the MC in Hugo's route, she mentions that Zeus has booming voice.
- Though he's nobility, many people have a hard time believeing this due to his behaviour. In Rembrandt's route, he tries to have an audience with Queensblade's monarch, Queen Zenobia or General Smith, one of the most influential person in Queensblade's court. He even tries to use his family name to get pass the guards. However, the guards don't beleive that a person like Zeus is from the House of Brundle and they have to retreat. Hiro mentions that his lack of class has made everything worse. Even Willem has to admit that it never crossed his mind that Zeus was a noble descendant.