Hinata might show up as well. Her relationship with Naruto can develop in new ways in different dimensions. For instance, in a dimension where Naruto is in a more dangerous situation, Hinata's love and support could be a key factor in his journey.
Jiraiya often appears. Since he was Naruto's mentor, when Naruto travels back in time, Jiraiya can play an important role. He could be the one to initially believe Naruto's story about coming from the future. Another common character is Kakashi. Kakashi was Naruto's teacher and his presence in the time - travel story can add a lot of interesting interactions, like Naruto showing Kakashi things he wouldn't know yet in that timeline.
Sasuke is often featured alongside Naruto in these fanfictions. Their rivalry and friendship make for interesting storylines when combined with the power of the Final Flash. For example, Sasuke could be in a situation where he needs Naruto's Final Flash to help him in a fight against a common enemy.
Obviously Naruto himself is a common character. Sasuke might also be there, perhaps as a rival or an ally in this devil - infused Naruto's story. Kakashi could be around too, as a mentor figure trying to guide Naruto through his new, darker path.
Naruto himself is obviously very popular. Since it's his name in the fanfiction title, he's often the main character traveling through dimensions. Sasuke is also common, as his complex relationship with Naruto can be explored in different dimensions. Kakashi is another popular choice, his skills and wisdom can play interesting roles in different dimension settings.
Doctor Strange often appears in Spiderman dimension travel fanfiction. Since he is an expert in the mystic arts and has knowledge about different dimensions, he can be a guide or an accidental cause of Spiderman's dimension travel. Another common character is Venom. In different dimensions, Venom can have different forms and motives, which makes for an interesting story when combined with Spiderman's dimension - hopping adventures.
Sakura could be one of the main female characters. She has a long - standing relationship with Naruto in the original series, so it would be interesting to see how their dynamic changes in a harem - like situation in a different dimension. Hinata is also a likely candidate, given her deep feelings for Naruto. Her shy but determined nature would add an interesting element to the harem story.
Well, Naruto himself is obviously a common character. Sasuke also often makes an appearance, either as a rival still or as someone who has a change of heart and decides to join Naruto's training. Kakashi might show up too, to give some guidance or check on Naruto's progress.
Sasuke could also appear in some fanfictions. Maybe he comes to visit Naruto in his isolated place, and they have a heart - to - heart talk that helps them resolve some of their past issues.
Sasuke is often a common character. He might have a different reaction to Naruto's banishment compared to the original story. Maybe he decides to join Naruto outside of Konoha or tries to find a way to get him back. Kakashi could also be there. He might be conflicted about Naruto's banishment and could play a role in either helping Naruto secretly or trying to uphold Konoha's decision.
Jiraiya could be another one. Since he was Naruto's mentor, he might go after Naruto when he's kicked out and continue to train him in secret.