Well, obviously Harry Noctis is one of the main characters. He is usually the center of the story, driving the plot forward with his actions and decisions.
The main characters are obviously Kenny Crow and Noctis. Kenny Crow could be a magical or otherworldly creature, perhaps with the ability to fly or some form of magic related to nature. Noctis is likely a heroic figure, maybe a prince or a warrior, with his own set of skills and a noble goal to achieve in his world.
In a fanfiction, Noctis and his friends could be summoned to Hogwarts by Dumbledore because he senses a great danger approaching that only their combined powers can defeat. Noctis might initially be suspicious of the wizards, but as he gets to know Harry and his friends, he realizes they share the same goal of protecting their respective worlds. They could then train together, with Noctis teaching the wizards some combat techniques and the wizards teaching Noctis about spells.
I'm sorry, I have no information about the main characters in 'jus primae noctis light novel'. However, in most light novels, the main characters often have distinct personalities. They might be brave, intelligent, or have some flaws that make them more relatable. Maybe in this light novel, there are characters who are on a quest, or characters who are trying to protect something or someone important.
One popular story could be 'Harry Noctis and the Lost Magic'. It often features unique adventures of Harry Noctis in a magical realm filled with strange creatures and new spells.
In this fanfiction, there could be new characters introduced as well. There might be an older, wiser wolf that takes Harry under his wing, so to speak, and teaches him about the ways of the wolf. Or perhaps there's a villain who is specifically after wolf - Harry for some dark purpose.
Obviously, Harry is the main character as he is the duke. But often, there will be his loyal servants like his butler, Mr. Thompson, who helps him manage the ducal estate. And there could be a female lead, perhaps Lady Elizabeth, who is a love interest and also provides support in different situations.
There could be new characters introduced in this fanfiction. For instance, a powerful dark wizard who is an equal match for the ruthless Harry. This character could be the main antagonist, constantly challenging Harry and forcing him to use his ruthlessness to the fullest. Or perhaps a mysterious mentor figure who helps Harry hone his ruthless side, teaching him skills and knowledge that are not part of the traditional Hogwarts curriculum.
There could also be some new characters introduced specifically for this fanfiction. Maybe a magical creature who has knowledge about catgirls and helps Harry come to terms with his transformation and use his new abilities in the best way possible.
The main character is Harry. However, we can expect to see some powerful demigod figures. Maybe there's a demigod version of Draco Malfoy who has a different relationship with Harry in this new context. Also, the gods from different mythologies might make appearances, like Zeus or Odin. Their interactions with Harry and how they influence the plot would be fascinating to read about.
Obviously, Harry is one of the main characters. And then there are the shipgirls, though which specific shipgirls are main characters can vary from one fanfiction to another. It could be some of the more well - known shipgirls like Bismarck or Yamato.