A villain like Shigaraki would likely be interested in the power levels in the MCU fanfiction. He's always looking for ways to increase his own power, and seeing the various powerful artifacts and abilities in the MCU might give him some ideas. He could think about how he could use similar things in his own plans to take over the MHA world.
If the MHA characters were to react to a Mastermind fanfiction, some would be more accepting than others. Characters like Ochaco might find it really exciting. She's a fan of the heroes herself, so seeing different takes in fanfiction would be like getting a new perspective on the MHA world. However, characters like Shoto, who are more reserved, might be a bit hesitant. He might need some time to process what he's reading. But overall, it would be a very interesting scenario as it would show how the characters view different interpretations of their world.
Some characters would be shocked. For example, if the fanfiction had a really dark and unexpected Mastermind plot, like a hero turning out to be the mastermind of all the villains' plans, characters like Tsuyu would be very taken aback. She'd probably question the motives behind such a plot. Then there are characters like Denki. He might be more into it if it had some cool action scenes in the fanfiction, regardless of how out - of - the - blue the Mastermind storyline was. And Nejire would probably be super curious about the emotional depth of the characters in the fanfiction.
MHA characters might also be a bit jealous of some of the superpowers or unique abilities in other anime fanfiction. In their world, quirks are relatively well - defined, but in some other anime, there are really out - of - this - world powers. They could be in awe of the creativity and at the same time, try to figure out how they could incorporate some of those ideas into their own fighting styles. Like, if they read a fanfiction about a character who can manipulate time, they might start thinking about how they could use their quirks in a time - related way.
Bakugo might initially be in denial. He's always had a complex relationship with Izuku, and seeing him in such a state could shatter his world view. He might become more withdrawn or, on the contrary, be spurred into a violent rage against whoever was responsible.
Well, Bakugo might scoff at first. He'd probably think Batman is too brooding and not as straightforward as he likes his heroes. But then as he reads more of the fanfiction, he might grudgingly admit that Batman's detective skills are cool. Deku, on the other hand, would be super interested. He'd be analyzing every move Batman makes in the fanfiction, taking notes in his head about Batman's strategies and how they could be applied in his own hero work. Uraraka would be more focused on the relationships in the fanfiction. She'd be all 'aww' at the cute moments and feel for the characters when they're in trouble.
Millions and AFO were both important characters in My Hero Academy. They both had great strength and abilities. However, who was stronger depended on character settings and battle strategy.
Million Passers was one of the strongest heroes in My Hero Academy. He had invincible walls and unparalleled strength. His ability can resist all attacks and can reflect enemy attacks through walls. In battle, he usually adopted a static defense strategy to defend against the enemy's attacks by holding his position. Thus, the static defense of a million was very strong.
AFO was another very powerful character in My Hero Academy. He had the ability to fly and teleport. His ability allowed him to teleport anywhere and attack the enemy's weakness. In battle, he usually used dynamic attack strategies to defeat the enemy by moving quickly and attacking. Therefore, AFO was very powerful in terms of dynamic attacks.
Both Million Passers and AFO were very powerful characters. The stronger one was, the more determined the character's combat strategy and settings. Under certain circumstances, the Million Passers may adopt a more static defensive strategy, while under certain circumstances, AFO may adopt a more dynamic offensive strategy.
In most of such fanfictions, they might create evidence like hidden past connections. For example, AFO could be secretly involved in Izuku Midoriya's (Deku) family history. Maybe he had a relationship with Deku's mother long ago, which led to Deku's birth. But it's all fictional speculation within the fanfiction world.
One common plot twist is that Deku discovers the truth about his father in a moment of great crisis. For example, when he's facing off against AFO in a big battle, AFO reveals the truth to him, which completely shakes Deku's world view.
Well, I think some of the MHA characters would be really confused. For example, Midoriya might be a bit bewildered by the different superpower concepts in the MCU fanfiction. He's used to his own world's Quirks, and suddenly seeing things like the Infinity Stones and Asgardian magic would be a lot to take in.