Overall, the Record of Ragnarok manga and mangs share a basic framework, but there are variations in details and plot points. Some aspects might be emphasized differently depending on the medium.
Mikey might be a character created to tell a story about Pop Rocks. He could be a fictional child used to illustrate the appeal or novelty of these candies. For example, he could be a curious and adventurous little boy who wasn't afraid to try new things, like Pop Rocks, which were quite different from other candies at the time.
In 'ghast x mangs fanfic', a prevalent theme might be the exploration of their differences. Ghasts and mangs are presumably distinct entities, and writers may focus on how they overcome those differences. Additionally, themes of loyalty and mutual understanding often come up. As they interact, they might learn to trust and rely on each other, which can be a central part of the story. There could also be themes related to a shared goal, like saving their world or something similar, which forces them to work together despite their differences.
In many fanfictions, Mikey is the optimist. He looks at the world with a positive outlook and tries to find the good in Rahzar. His friendly nature makes it easier for him to approach Rahzar, even though Rahzar might seem intimidating at first. Rahzar is usually depicted as having a lot of strength and power. He's a force to be reckoned with, but his character can also be complex, with hidden emotions that Mikey helps him uncover.
Well, it could be anything from character designs to the tone of the story. Maybe a manga has more detailed world-building that doesn't fully translate to the anime, or vice versa.
I'm not sure. 'A you wish prince mangs' could potentially be part of a code or a private language that only certain people know the meaning of. Or, it could just be a string of words put together without any specific logic.
April and Casey might also be part of this fanfiction. April could use her reporting skills to try and figure out what's going on with Mikey's mutation, and Casey would be ready to fight any new threats that come along because of Mikey's changed state. Also, Splinter, as their sensei, would be guiding them all through this difficult time, providing wisdom and training to help Mikey control his new powers if he has any.