Eventually, Eren might start to investigate the reasons behind Mikasa's betrayal. If he discovers that there are more complex factors at play, like she was forced or there was a misunderstanding, he could feel a mix of guilt for his initial reaction and relief that their relationship wasn't as broken as he thought. However, if he finds out that she truly betrayed him out of her own will, he might become even more determined to carry out his plans, whatever they are, without her.
Well, there are also those characters who might be a bit shocked or confused. Take Levi from Attack on Titan. He's a very serious and no - nonsense type of character. If he were to read some of the fanfic about him that deviated too much from his own self - perception, like being made into a comical or overly emotional character in the fanfic, he might be taken aback at first. But then he might also realize it's just a different interpretation and not take it too seriously.
Well, it depends on the nature of the fanfiction. Some anime characters might be amused if the fanfiction is light - hearted and full of comical situations. For example, if it's a fanfic about a cooking competition among the characters from a shonen anime, they might react with good - natured laughter and competitiveness. They could also be confused if the fanfiction takes their story in a very strange or unexpected direction, like suddenly making a character from a historical anime end up in a space adventure.
Some fans are heartbroken. Eren is a very popular character, and his death can be a huge emotional blow. They might write comments expressing their sadness and disappointment.
Eren would probably be very curious. He's always been eager to learn and understand new things. Meeting kids from another time would be fascinating for him. He might ask them a lot of questions about their world and how it differs from his. Levi, on the other hand, would be more guarded. He'd be suspicious at first, but once he realizes they're not a threat, he might start to warm up and show his more protective side towards the kids.
Armin could be one of the main characters. He might be the one who offers the most logical advice to Eren during his pregnancy. For example, he could help Eren figure out how to deal with the medical aspects if the world in the fanfiction has different rules for male pregnancy. Another character could be Mikasa. She would probably be very protective of Eren, just like she always is. She might be the one to stand up for Eren against any discrimination or threats he faces because of his pregnancy.
Kakashi would be very observant. He would look for how the fanfiction writers understand the world of Naruto, the values and the moral lessons. He might even use some of the creative ideas from the fanfiction in his own teachings if he thought they were valuable and in line with the spirit of the original story.
There could be characters who are outraged. If the fanfiction distorts their personality or makes them do things completely against their nature, they may be very angry. For example, a noble character made to act like a coward in the fanfiction would likely not take it well.
They might be confused at first. RWBY has its own unique lore and concepts that are different from many anime. So anime characters may need time to understand things like Grimm and Huntsmen. For example, if Goku from Dragon Ball was watching, he'd probably be like 'What are these strange monsters?'.
They could be surprised. The fanfiction might show them in scenarios they never imagined, like a shy character being in a very bold and adventurous situation.