Gwen could be really interesting. She could have developed different powers in a different time period that Ben discovers when he travels back. Also, Grandpa Max in his younger days would be cool. He might have been involved in some secret time - traveling adventures that Ben uncovers. And Vilgax from different points in time could add a lot of drama. Maybe a younger Vilgax who is still learning and more vulnerable, or an older, more powerful Vilgax from a far - off future.
Definitely Kevin. Imagine Ben traveling to a time when Kevin first got his powers. They could form a different kind of alliance or have a completely different relationship compared to what they have in the present. Another character could be Azmuth. If Ben travels to the past to meet Azmuth when he was creating the Omnitrix, there could be some really fascinating interactions. And don't forget about the Forever Knights. They could have different motives and levels of power in different time periods, and Ben could get caught up in their schemes while time - traveling.
Definitely Ben himself. His ability to transform into different aliens makes for interesting scenarios in different time periods. For example, in the past, he could transform into an alien that was thought to be a myth, causing all kinds of chaos or amazement.
Ben Tennyson is definitely an interesting character to include. His ability to transform into different aliens gives a lot of possibilities for the story. Finn the Human is also great. His adventurous spirit and his sword - fighting skills can add action to the fanfiction. Jake the Dog can be really fun too, with his shape - shifting abilities. And of course, Princess Bubblegum, her intelligence and leadership can bring a different dynamic to the story.
Issei himself is of course very interesting. His reactions to different time periods and how he uses his knowledge from the future can be really engaging. Then there's Rias. Her presence can add a layer of complexity, especially if she has different relationships with Issei in different timelines. Another interesting character could be Vali. His rivalry with Issei can take on new dimensions when time travel is involved, like competing in different historical battles or for the affections of a character in a different era.
Morgan could be an interesting addition. He might accidentally get caught up in Chuck's time - travel adventures. His comical nature could provide some light - hearted moments in an otherwise complex time - travel plot, like when he misunderstands the technology or customs of a different time.
One popular character type is the time - traveling scientist. They might be interested in studying the scientific knowledge or lack thereof during WW1. For example, they could try to introduce new medical techniques. Another is the adventure - seeking young adult. They see the time travel as an opportunity for a great adventure and end up getting involved in the war in unexpected ways. Also, a war journalist from a different era could be a great character. They could document the events of WW1 in a new light.
One character that would be interesting to include is Abel Gideon. He was already a part of Hannibal's world, and in a time - travel story, he could have a different role. Maybe he travels with Hannibal or is sent to a different time to hunt him down. Also, Freddie Lounds could be a great addition. She's always looking for a good story, and Hannibal's time - traveling would be the ultimate scoop. And then there are the victims. What if some of the victims from different time periods were able to come back and haunt Hannibal? That would add a spooky and interesting element to the fanfiction.
Definitely Albus Potter. Since he's Scorose's contemporary and is also related to the Potter family, he could add some interesting family dynamics to the story. His own experiences and abilities can play a role in the time - travel adventures.
One of the most interesting characters to include would be Orochimaru. His thirst for knowledge and immortality could lead to some really wild plot twists in a future time - travel fanfiction. Then there's Shikamaru. His intelligence could be used to strategize in a future full of new challenges. And Sakura. Her growth as a ninja and her relationship with Naruto and the others could bring a lot of depth to the story.
One character that would be fascinating is Medivh. As a powerful mage with knowledge of time and magic, he could either be a helper or a hindrance to Anduin. He might know secrets about the time travel that Anduin is doing and use it to his own ends. Another interesting addition could be Illidan Stormrage. His complex relationship with power and his own past actions could make for some intense interactions with Anduin as he travels through time.
Max Tennyson is a great character to include. He has a lot of wisdom and experience which can add depth to the story. He can be the one to give Ben and Gwen advice during their adventures. Another good character is Kevin Levin. His complex relationship with Ben and Gwen can create interesting plotlines, especially if there are conflicts or reconciliations involved.