Well, consider this. The Upside Down in Stranger Things could be a result of some dark magic from the Marvel universe. The Stranger Things characters, being the only ones who know about it, are recruited by Doctor Strange. Eleven could be trained by Strange to better control her powers and use them in a more magical way. The other kids could learn about different dimensions from Strange and use that knowledge to help protect the Marvel universe from threats that might be coming from the Upside Down.
Some Homestuck characters could become allies or enemies of the various Marvel factions. The Homestuck trolls' complex social structure could be at odds with the more straightforward good - vs - evil dynamics in the Marvel world. For instance, a troll who is used to a cutthroat hierarchy might initially have trouble adjusting to the Avengers' more collaborative approach.
The Stranger Things characters would bring their own unique personalities and skills. For example, Joyce could be like a Muggle mother figure who somehow gets involved in the wizarding world and helps out with her no - nonsense attitude. Hopper could be an Auror - like figure, using his investigative skills to track down dark wizards or creatures that have a connection to the Upside Down. The kids would have to adapt to the rules of Hogwarts, but also introduce their own ideas. They might not be used to using wands, but they could find ways to incorporate their own abilities with magic, like using Eleven's powers to enhance a spell or something.
In terms of power levels, the Immortal Mage could have powers that are on par with the likes of Scarlet Witch or Doctor Strange. Their immortality might also come with the ability to regenerate from any injury, making them a formidable force. They could also have the power to travel through different dimensions, which is a common theme in Marvel. This would allow them to access hidden knowledge and artifacts that could be used to either protect or disrupt the Marvel Universe depending on their motives.
Superman could fit in as an outsider at first. He'd be this super - powerful being that the Marvel characters don't really understand. His powers might be seen as a threat initially. But over time, he could become an ally. For example, he could help the Avengers during a major crisis, like an invasion from another dimension. His flight and heat - vision would be useful assets.
The Chosen Undead from Dark Souls could be seen as a mutant in the Marvel Universe with their ability to keep coming back to life. They might be shunned at first like many mutants are, but then prove their worth when facing threats. Their combat skills with swords and shields would be a unique addition to the fight scenes in the Marvel Universe. For example, they could fight alongside Wolverine, and their different fighting styles would create an interesting contrast.
Well, it depends on how his powers are perceived in the Marvel Universe. Naruto's chakra is a powerful force. If it's seen as something similar to mutants' powers, he could be considered a very powerful mutant. But compared to characters like Thor or the Hulk, his power might be more about finesse and strategy. His rasengan can cause a lot of damage, but he also has to get close to his opponents. So, he might not be as overpowered as some of the top - tier Marvel characters, but still very formidable.
Dark Naruto might be introduced as a threat in a Marvel fanfiction. His darker nature could lead him to target powerful artifacts in the Marvel Universe, thinking they could enhance his power. For example, he could go after the Infinity Stones. His combat skills and unorthodox powers would make him a formidable adversary for characters like the Avengers.
Superman could fit into the Marvel Universe in several ways in fanfiction. Firstly, his origin could be tweaked a bit. He could be an experiment gone wrong in a Stark Industries lab that gave him his powers. This would immediately connect him to the Marvel world. His powers would still be his trademark ones like flight, super strength, etc. He could then become a sort of protector of a particular city in the Marvel Universe, like New York. He would interact with the local heroes and villains. His presence would disrupt the power balance a bit, and some villains might target him specifically. But with his unwavering moral compass, he would stand up to them and become an important part of the Marvel Universe's tapestry of heroes.
The characters from 'A Wrinkle in Time' could be introduced as mysterious travelers in the Naruto universe. Meg, for example, could be seen as a foreigner with strange powers that initially confuse the ninja. Her ability to understand complex concepts quickly could be seen as a form of ninjutsu - like intelligence. Calvin could be a natural athlete in the Naruto world too, perhaps using his physical abilities to learn ninja combat techniques faster than others.
In fanfiction, Ben could be a sort of hero - in - the - shadows in the Fairy Tail universe. He doesn't directly join the guild but helps them out when they're in big trouble. His alien forms give him an edge in battles against powerful dark mages. The Fairy Tail characters would gradually become aware of his presence and start to rely on him, even if they don't fully understand his powers at first.