Well, apart from the regressed son - assassin, there might be servants in the duke's household who are aware of his secret. There could be an old wise man or woman who has some knowledge about the regression and gives him advice. And then, there may be powerful lords or knights who are either on his side or oppose him. These characters together would create a complex web of relationships and drive the story forward.
Well, it might be about a duke's son who has regressed in time. As an assassin, he could be using his new - found knowledge from the regression to his advantage. Maybe he's seeking revenge or trying to change his family's fate.
The God of War must be one of the main characters in 'god of war regressed to level 2 novel'. There could also be other characters like his former comrades who might help or hinder his journey to regain his power. And there could be the antagonists who are responsible for his regression or those who take advantage of his weakened state.
I don't know the exact main characters since I haven't read it. But typically, there would be the protagonist who has the regressed king's power, and probably some antagonists who oppose them.
I'm not entirely sure as I haven't read it in full. But usually, the martial god who has regressed to level 2 would be a main character. There might also be a mentor - like figure who helps them on their journey back to power.
In 'the duke romance novel', the duke is the central male figure. He has all the trappings of nobility. The female protagonist is an important main character too. She might be an artist or a writer in some cases, which makes her stand out. There could be a villainous character as well, perhaps another noble who wants to ruin the duke's relationship or take his title. And don't forget the friends of the main characters, they can influence the plot by either helping or hindering the relationship.
Typically, the assassin is one of the main characters. This character is likely to be highly skilled in combat, stealth, and deception. Then there's the king who is the target. He might be portrayed as a powerful but perhaps corrupt or tyrannical figure. There could also be a mentor figure in the assassin's past, who taught them their skills and whose influence still lingers.
I don't know for sure since I haven't read it. But typically, there would be the assassin as a main character. There might also be the assassin's handler or employer if they play a significant role in the events leading to the death. And perhaps an antagonist, someone who has a strong motive to kill the assassin.
The main character in the 'american assassin novel' is Mitch Rapp. He is a young man who is out for revenge after a personal tragedy. Other characters include the CIA officials and operatives who interact with him. These characters provide support, opposition, or guidance to Mitch Rapp at different points in the story. Some may be his mentors during training, while others might be his colleagues on dangerous missions.
Since I don't know the specific 'assassin light novel', it's hard to say. But usually, there would be the assassin as a main character, perhaps also a mentor or a target.
The main characters are likely the woman and the duke.