Well, Batman is an obvious choice. He has the resources, the intelligence, and the motivation to venture into other dimensions. If there's a threat in another dimension that could potentially affect Gotham, he'd be there. Harley Quinn could also be a character who gets involved in dimension travel. Maybe she's chasing after the Joker who has somehow ended up in another dimension. And Oracle, with her technological expertise, could accidentally stumble upon dimension - traveling technology and end up in a different dimension while trying to fix or improve it.
One interesting concept could be the different versions of characters from alternate dimensions. For example, a Batman from a dimension where Gotham is a utopia instead of a crime - ridden city. Another concept might be the unique powers or abilities that come with traveling between dimensions, like the ability to manipulate the fabric of reality in ways that are not possible in a single dimension. And there could be crossovers with characters from other fictional universes that are made possible through dimension travel.
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.
Gwen Tennyson also often plays an important role. In the dimension travel fanfiction, she might accompany Ben on some of his travels or be a key figure in the dimension he travels to. Her magic powers can add an interesting dynamic to the story, especially when combined with Ben's alien forms.
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.
One of the most used tropes is the 'chosen one' idea in alternate dimension travel fanfiction. The character from our dimension is somehow the key to solving a big problem in the alternate dimension, like a prophesied savior. This gives them a sense of purpose and importance in the new world. There's also the trope of bringing back knowledge or technology from the alternate dimension. It's like when a character discovers a new form of energy or a revolutionary medical treatment in the other dimension and tries to bring it back to their own world to make a difference.
Dimension travel in Harry Potter fanfiction is really exciting. Sometimes, it allows the main characters to gain new powers or knowledge from other dimensions. They might meet alternate versions of themselves or their friends. It can also be a way to fix things that went wrong in their original dimension. For instance, if a character made a big mistake, they could travel to a dimension where that mistake didn't happen and learn how to correct it in their own world.
I really like the fanfiction 'Superboy in the Strange Dimensions'. In this story, Superboy discovers dimensions where the laws of physics are completely different. It's a fascinating read as he tries to adapt and use his powers in these new environments. There are also some great character interactions that add depth to the story.
One possible fanfiction could be about Naruko traveling to different dimensions in the Naruto universe and meeting alternate versions of her friends and enemies. She might learn new jutsus or gain unique powers from these encounters.
One great 'Dimension Travel Naruto Fanfiction' is 'A New Path in Another World'. In this fic, Naruto gets transported to a different dimension where the ninja world has some unique and strange rules. It's really interesting to see how he adapts his skills to this new environment.
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.