The detective character, if there is one. They usually have a complex personality, with a sharp mind and a lot of intuition. Their methods of solving the mystery would be really interesting to follow.
The person who has the most to lose if the truth comes out. They would be constantly on edge, trying to manipulate the situation and the other suspects. Their desperation would make them a very interesting character to watch as they try to cover their tracks.
Maybe the train itself has some sort of hidden compartment or mechanism that is related to the crime. And the people who know about it are the ones involved in the mystery. So as the story unfolds, the discovery of this train - related secret could be a major plot twist.
I think Godric Gryffindor would be really interesting. He was one of the founders of Hogwarts and was known for his courage. He could train Harry in the Gryffindor values in a more profound way. He might teach Harry how to truly be brave in the face of extreme danger, not just the kind of bravery that Harry already has but a deeper, more instinctual kind. He could also show Harry some of the original Gryffindor magic that has been lost over time.
A tourist who has visited Yosemite Falls multiple times. On the surface, they seem like an ordinary visitor, but in fact, they are part of a group that is planning something big. They use their tourist guise to scope out the area around the falls and make their move when the time is right.
I think Robin himself can be the most interesting. He's young, full of energy and has this eagerness to prove himself. He's constantly learning from Batman and at the same time, trying to find his own identity as a hero in Gotham.
One of the most interesting interactions would be between Weiss and Blake. Weiss, coming from a high - society background, and Blake, who has been an outcast, could have some really deep discussions about acceptance and change. Another interesting pair would be Ruby and Pyrrha. Ruby could learn a lot from Pyrrha's combat experience and Pyrrha could be inspired by Ruby's unique way of looking at the world.
Ladybug would be an interesting character to pair him with. Given their existing relationship in the original story, Chat Noir's trait of seeing the good in everyone could add a new dimension to their dynamic. He could help Ladybug see the good in some of the more difficult villains they face, or in characters that she might be more skeptical about. This could lead to different strategies in fighting evil and also deepen their emotional connection.
A character who is initially very meek but transforms into a vengeful force could be fascinating. For instance, a bullied student who finally snaps and decides to take revenge on the bullies in a very calculated way.
I'm not sure which novel you're referring to because you didn't provide enough information. However, if you are referring to the plot of a certain novel, I can provide you with some possible clues. If you're referring to a male protagonist who obtains the memories of everyone on the train in a train disaster, this plot may appear in some science fiction or fantasy novels, such as the " Three-Body Problem " series, the " Star Trek " series, etc. In these novels, the male protagonist might have obtained the ability to read other people's memories through some means that surpassed human cognition. This plot usually involved some philosophical or psychological thinking because the male protagonist's behavior could have a profound impact on human consciousness and memory. If you can provide more information such as the title of the novel, the identity of the male lead and the storyline, I will be more than happy to provide you with more help.
Perhaps a new character who has a hidden agenda. Maybe someone who has a connection to a current case Gibbs is working on and doesn't want him to get too close to the truth. This person might be working for a larger criminal organization and sees Gibbs as a threat.
Kakashi could be an interesting character to further train Naruto. He already had a role in Naruto's early training, but in fanfiction, he could teach Naruto more advanced Sharingan - related techniques, even if Naruto doesn't have the Sharingan. Another could be Jiraiya's spirit. Even though he's dead, his spirit could come back to offer more sage mode training or teach Naruto some secret jutsu he never got to before.