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.
Well, Akeno is a character that can make the fanfiction more interesting. Her relationship with Issei can be explored in different timelines. She might have different personalities or powers in different times. Xenovia is another one. Her strong beliefs and fighting skills can lead to some exciting storylines in time - travel scenarios. For instance, she could be involved in battles in the past that change the future. And don't forget Koneko. Her growth and development can be shown in different time periods, and how she interacts with Issei in different timelines can be really fascinating.
I think Sirzechs could be an interesting character in Issei time travel fanfiction. His power and influence in the original story can have different implications when Issei travels through time. Maybe he becomes an ally or an obstacle in a different time. Grayfia is also a great addition. Her loyalty and skills can play important roles. For example, if Issei travels to a time when there's a threat to the Gremory family, Grayfia's actions can be crucial. And of course, Azazel. His knowledge and schemes can be even more intriguing when time travel is in the mix.
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.
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.
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.
Rick is an obvious choice. His intelligence and knowledge of the multiverse can add a lot of depth to the time travel story. He could be the one helping Morty fix the problems caused by time travel, or he could be the cause of the problems in the first place. Another interesting character is Summer. She could get involved in Morty's time travel adventures, and her different perspective as Morty's sister can bring new elements to the story. Maybe she's jealous of Morty's time - traveling and tries to tag along.
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.
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.
Fugaku himself is obviously a very interesting character. His journey through time allows us to see different sides of him. He might be a strict and stoic clan leader in his original time, but during time travel, we can see his vulnerability and his struggle to adapt to different situations. Another interesting character could be his younger self. The interactions between Fugaku from different time periods can be really fascinating, as he tries to guide or understand his younger self. Also, any characters who are aware of the time travel and try to manipulate it for their own gain, like a rogue ninja who wants to change history to gain power, can add a lot of intrigue to the story.
Definitely Naruto. Even if it's a Team Konohamaru time travel fanfiction, Naruto's presence can add a lot of excitement. He could offer his unique perspective and skills, and his interactions with Konohamaru and the team would be really interesting, especially if they travel to a time when Naruto was younger or not even born yet.
Jiraiya would be an interesting character. His relationship with Naruto could be explored in a new light if Naruto travels back in time. Jiraiya could teach Naruto different things or Naruto could use his future knowledge to help Jiraiya in his missions.