The reactions of pro heroes to Deku fanfiction could vary greatly. Pro heroes who are more outgoing and friendly, like Mirio, might actively seek out Deku fanfiction just for fun. He could be the type to laugh out loud at the creative and sometimes wacky ideas in the fanfiction. However, more serious pro heroes, such as Aizawa, might initially be skeptical about the whole concept of fanfiction. But if the fanfiction has some deep insights into Deku's character and his journey, Aizawa might start to respect it more.
Some might feel honored. They see it as a form of recognition of their importance in Deku's story or in the overall My Hero Academia universe. For instance, Iida could see his friendship with Deku being explored in a fanfiction as a compliment to their real - life bond.
I don't know for sure. The ending of such a manga can be quite unpredictable and might not have been revealed yet. You could try discussing it with other fans to get their speculations.
Green Lantern would use his power ring to create various constructs. He could create a large, impenetrable cage around Superman to stop him from escaping with Batman. He'd also use his ring to scan Superman for any signs of external influence, like magic or some sort of alien technology that's making him act this way.
I'm not really sure if they end up together. Different people might have different interpretations. Maybe you can dig deeper into the manga and form your own conclusion.