Spiderman has his super strength, agility, and the famous spider - sense. In comparison, MHA characters have a wide variety of quirks. For example, Todoroki has his ice and fire powers. Spiderman's agility might be on par with some of the more acrobatic MHA characters like Sero. But his spider - sense gives him an edge in combat that most MHA characters don't have. However, quirks like All Might's super strength can rival Spiderman's own strength.
One aspect of Mha Tomura x Himiko fanfiction could be the exploration of their unique relationship dynamics. Tomura's complex character, with his goals and his own brand of villainy, and Himiko's rather eccentric and blood - loving nature can create some really interesting interactions. Writers might delve into how they understand each other on a deeper level, perhaps sharing a common view of the world that is different from the heroes' perspective.
No, it's not appropriate. Deku is a character with his own depth, goals, and story within the MHA universe. Fanfic should aim to explore his hero journey, his relationships in terms of mutual respect and support, not create content that focuses on inappropriate or disrespectful ideas like this.
His spider - sense would be a very useful power in the MHA universe. Given that many battles in MHA involve sudden attacks and surprises, Spider - Man's ability to sense danger before it happens would give him an edge. He could use this to warn his MHA allies and prevent ambushes. Also, his super strength would make him a formidable force against the powerful villains in the MHA world. He could hold his own against even the strongest quirks, like All - Might's strength - based quirk.
The plot involves Rimuru's journey from being a rather weak (initially) slime to becoming a very powerful being. He meets many interesting characters. For example, there are the goblins he befriends early on. Rimuru helps them improve their living conditions. As the story progresses, he also has to deal with the threat of other more powerful monsters and even some human kingdoms that view his growing power with suspicion. In general, it's a story full of adventure, growth, and the forging of relationships in a magical and dangerous world.