Long ago, Lucious the prince of the Kingdom of Nighttime and Claudia the princess of the Kingdom of Daylight, fell in love with each other despite their kingdoms being at war. Claudia’s father was against their relationship and tricked Lucius into believing that if he got to escape the labyrinth he could meet Claudia again and marry her. Lucious then was cursed and trapped inside the “Underground Labyrinth” where the Night Classes are held. The price for this curse was too high and all descendants of the Daylight Kingdom got cursed in return, being transformed into a pig every time someone kissed them. This caused a crisis within the Kingdom of Daylight’s family members, with some running away, others dying and later causing the fall of Kingdom itself.
It was unknown what happened to Claudia afterwards. However, in his route is learned that the princess never married and as time passed by, she came to realize that she'd never be with him again, yet she never stopped looking for a way to free Lucious. In the end, her last desire was to reunite once again with him and to tell him that she'd always love him and that it was okay for him to move on. She got her wish thanks to Liz, Zeus and Hiro.
In Zeus’ route, at the beginning of Season 6 arc, Lucious wasn't aware of how much time had passed, still believing that he could meet Claudia again and marry her. He didn't have any idea that part of the curse of the labyrinth was that time never passes by there. Therefore, he couldn't know that his beloved Claudia had died a long time ago. Other parts of the labyrinth’s curse were that, he couldn't know the exit, which kept him wondering around aimlessly. He was always hiding from the guardian which was a Minotaur.
At first, Lucious and Liz meet when she got lost trying to find her way to the Night Café, ending up at the entrance of the Labyrinth. After boarding the train in underground station, Liz and Lucious tried some small talk but Liz could not tell if Lucious was trustworthy or not. However this first encounter goes wrong when Liz shows him the brooch that Headmaster Rembrandt had given her as a good-luck charm and Lucious, knowing the truth behind the item, tries to takes it from her by force. Liz escapes thanks to Zeus who was unaware of what had happened between Lucious and her. Eventually Liz finds out the true meaning behind Lucious behavior. She ends up knowing of who Lucious was. Liz had heard about Lucious and Claudia in a fairy tale that told the story of the Daylight and Nightime Kingdoms that illustrated them as star-crossed lovers. After finding out who he was, Liz sympathizes with him and she unites with Zeus in finding a way to release Lucious from the labyrinth. Zeus takes of his own account to rescue Lucious when he meets him, going as far as to infringe the law by trying to take a rare and dangerous item to destroy the labyrinth and, therefore, set Lucious free. However, being quite tactless towards people feelings, Zeus doesn't take into consideration Lucious feelings on these actions, not even when mentioning to Lucious that a century has passed by since Claudia’s death.
When Lucious finds out that Claudia had died a long time ago, he gets so depressed that he asked to be destroyed along with the labyrinth. Liz convinces Lucious that although Claudia is no longer alive, he still has friends, like Zeus, who would give their lives for him thus proving that he is still loved. Zeus realizes his mistake on not considering Lucious' feelings and consoles him. The only thing that lasted for Lucious to remind of Claudia was an old painting that is hung in a studio. According to Liz, although the painting shows Claudia's beauty, Claudia appears sad. When she asks Lucious if he's not bothered by the sadness she displays, the prince responds that although he doesn't like to see her sad face, it is better than having nothing to remember her. According to Zeus, Claudia has much of the fault for Lucious being trapped in the labyrinth because she didn't fight for him hard enough and let him get cursed. However the prince doesn't think that way and still bears a deep love for her. At the end of Zeus' route, Liz and the others prefects tried to free Lucious from his prison. The Minotaur beast is defeated but this doesn't solve the problem of setting Lucious free.
In Klaus' Main Route II, Liz is still trying to find a way to release him from his prison, but other circumstance such as the stolen items or the BBW (Big Bad Wolf) case leave this search aside.
In Hiro's route is marked by Zeus that Liz has probably become Lucious' favorite person. This is seen when they go to see Lucious and Zeus calls him out, at first Lucious seems angry due to Zeus calling him "baby prince", but as soon as he sees Liz, he lights up and ignores Zeus. When the Night Prefect fell into a coma due to an accident in Hiro's trial, all the other prefects go to the entrance station to board the train that would take them to the Lake of Insanity. They all spot Lucious sitting on a bench like he was waiting for someone and when they question him about this he reluctantly tells them that Zeus hasn't visited him lately and therefore he was there waiting to see him.
At the end of Hiro's route, Hiro mentions that the relationship between Lucious and Liz was similar to him and Zeus, therefore he implies that they're more like brother and sister, which Liz says is an exaggeration because she doesn't know Lucious as well as Hiro knows Zeus but she hopes that one day Lucious and her could become like them.
Alfonse's route.- Lucious is not seen much in Alfonse's route because the MC is occupied with other things like the apparition of Hugo, the Black Robe Plague and the problems among the Goldstein brothers.
Caesar's route.- Caesar and Liz are trying to find the Star Sapphire that, according to some records, it was supposed to be in the world underneath the academy and everyone assumed it meant the labyrinth. So Liz, Caesar and Hiro are commanded by the headmaster to seek Lucious' help to find the Star Sapphire. Though they take a little detour, they eventually end up in Illusion station, the entrance of the labyrinth. They find Lucious there and ask him to help them. Liz shows him the coin. Lucious examines it and after he throws it back at Liz and scolds Caesar saying: "Basically, you're just to become someone eternally lost, too... Right, Baroque?". Caesar doesn't answer and Lucious is angered when he learns that he had been leading Liz with that coin without telling them about it. After that, Lucious leaves them shouting that he's not going to help them. Liz tries to get the thruth out of Caesar, but at that momento they're interrupted when Zeus summons them.
After other things happen to Caesar and Liz, Headmaster Rembrandt orders them and Hiro to resume their search for the Star Sapphire, asking them to hurry and find it before Hugo, for he fears that if Hugo finds it first, it will be catastrophic. Zeus joins the search too and Rembrandt thinks it's a good idea because he has a deep relationship with the Prince of Nighttime and he could persuade Lucious to help them. However, Lucious confronts Caesar once again, saying that if he hasn't told them the truth, he's not particpating in any plan they have. Caesar doesn't give him an answer and before Lucious shout more, Zeus grabs him by his collar and pulls him up in the air. Then he goes to check on some onyx doors that had something to do with the lapis lazuli coin.
Lucious' Route.- At the beginning, Liz's is shown enjoying the market on a day off at Gedonelune Town. Suddenly Hugo appears saying that what he's about show her something that could be a possible future. Then Liz is encountered by Hugo in the market and he expresses how wonderful it is to see the outside world. At first, Liz is not sure what to do, because the reason tells her that Lucious is still trapped in the labyrinth. But seeing Lucious enjoying himself makes Liz to play along with the dream. After a few moments, rain starts to fall. Lucious has an umbrella and guards Liz and himself under it. However, while Liz is savouring this moment, she spots a man and, before she realizes it, Lucious is gone. She, on the other hand, seems to get engulfed in some dark magic. Before she's totally trapped by it, she is woken up by Taffy.
Taffy had come to her room because he was being summoned by the prefects to meet them at the entrance of the labyrinth. When she gets there, she learns the entrance has disappeared. They ask Zeus to use magic circle that would get them at the other side of the entrance. With a lot of effort, Zeus manages to take them inside the labyrinth. They meet Lucious there and they tell him about the early problem they had with the entrance and ask him if he had had similar problems on his side. He mentions that the room where he likes to go is now blocked as well as several other places but he hadn't given it too much importance. Liz is worried due to her dream and also she sees these changes as a sign that the labyrinth is sort of collapsing, which only makes her feel that she has to hurry to find a way to free Lucious.
Liz leaves Lucious with the other prefects because she had class to give at first period. Walking through the grounds, she finds Yukiya and Elias and greets them. Before leaving the grounds, she finds a trail of blood and, along with their friends, they decide to follow it. They find Hugo and Headmaster Rembrandt fighting and the headmaster had been injured. They defend the headmaster and after Hugo flees, they take him to the infirmary where he faints due to his wounds. Liz wonders why Hugo attacked the headmaster, but Elias suggests to just wait until the headmaster recovers.
After the classes in the morning are over, Liz goes to the Prefect's office and after chitchating with Chica and Mischa, she decides to take a nap. Again, she seems to be in a lucid dream, because she sees herself in the town harbour and Lucious is there. Apparently it was a sort of continue of the dream she had had before. Lucious tells her how his dream was to travel and see the world, but because of his status, and because he was the future king of the Nighttime Kingdom, he couldn't leave his palace, let alone his country. Liz mentions that maybe now he's out of the labyrinth and with no responsability towards a title or a kingdom, he can do whatever he wants. Lucious says he'd like that and it'd be great if she was with him by his side, since she was the one who freed him. He tells Liz how beautiful the harbour view is and she says that Alfonse was the one who showed it to her in the first place. Lucious asks Liz if she likes any of his friends in particular and when she answers that she doesn't, he comments that though she might not like someone, that doesn't mean that some of her friends doesn't like her. Changing the subject, Lucious asks Liz where she would like to go next and suddenly the hooded man from the previous dream shows up.
Lucious and Liz put their guard on, specially when he attacks Liz and the prince mentions about Liz being the target. Lucious attacks him back but his spell had no effect. When, the hooded man starts to chant a spell, Lucious is seen worried because apparently he was using ancient magic (the same as Rembrandt) and the one he was about to use was destruction magic. Lucious tries to protect Liz and then she wakes up.
Mischa, who had offered to wake her up so Liz could get some rest, asks her about her dream and that she could interpret it for her. She then tells her what the dream was about. Mischa interprets Liz, specially the part where Lucious is either someone Liz really likes or that he's someone who has shown recent interest in her.
At the beginning of the arc Lucious is shown as a proud and non-talkative teenager. Lucious is shy and resistant to opening up to others. Although he's older (being trapped in the labyrinth for over 100 years) than the rest of the characters, his features and personality are still of a teenager. Zeus tends to tease him by calling him names such as "coward" or "little", which upsets him and denies it, but tends to be true, since Lucious tends to hide every time something out of the ordinary appears in the labyrinth, which is understandable because most of the the times is a monster that Zeus summons and Hiro dispatches to the labyrinth in order to save the students or the school.
In his route, he mentions to Liz that the reason he had been so whithdrawn with Zeus and the rest of the prefects at first was because after the school opened, many students at the Night Class entered the labyrinth out of curiosity. Lucious oftenly met them at some point, but then they'd move on to look other places of the labyrinth. Because they didn't have guidance magic, they'd eventually get lost and never met Lucious again, because it was part of the magic of the labyrinth. Therefore, Lucious got his hopes high believing he had found someone to talk to and then losing them. Zeus was the first one to keep his promise to come back and to keep him company, but because of hundred of years of dissapointments, Lucious was reluctant to trust him at first. Despite all that, Lucious slowly opens up to the prefects becoming their friend and caring deeply for Zeus and later Liz as well.
Lucious was also shown having “child-like” actions, for example, when losing against Zeus in chess, Lucious gets frustrated and demands to continue until he can win. As Zeus visits him on regular basis to play chess, Zeus tends to tease him, calling him names, ruffling his hair, etc, being their relationship compared with that of brothers. Also, in his route, the prefects notice that Lucious tends to be foul-mouthed despite being a prince. They get to conclusion that it's the result of being in the labyrinth for too long.
In his route and some spin-offs, Liz often says that Lucious is not honest with himself either. When she gets to know him better, she sees easily that his words don't match with his feelings. She tells him that as well, but he dismisses her comments.
As the many routes progress, Lucious is more assured of his friendships to the point of become Liz confident often listening to her love problems with either Klaus or Hiro, depending on the route. In his route, of course, he's seeing as a jealous guy commenting he has too much competition for her affection.
From his debut up until Caesar's route (Season 7), he was never seen using any kind of magic.
It's seen in his route that the pendant he wears works as an item to channel magic, the same a wand is used.
- Lucious' surname was revealed previously in app notification (mobile version only), right after Caesar's route release. As Solmare's app notifications had presented typos before, this information stood unconfirmed till his route was released.
- When Liz Hart (MC) first met Lucious at the underground station, it was left unclear as to whether Lucious led her onto the train in an attempt to trap her in the labyrinth or not.
- "A Day in the Night Class" spin-off is the first event where Lucious is shown in a CG. He's shown in the group photo after completing the Zeus and Hiro's route. It's also mentioned in this spin-off that Zeus brings Lucious some of the new food so he can try it out. Zeus tries to scare Lucious with paper ghosts, but Lucious isn't fooled by them and get rid of the paper ghosts easily.
- "Dwellers of Darkness" is the first spin-off where Lucious is given a role as a romanceable character for Liz (MC), and also included a new outfit/sprite for him.