Well, some might be amused. For example, Lucy would probably be both exasperated and endeared as in fanfiction Natsu might get into even wilder adventures. Gray would likely be competitive as always, ribbing Natsu about his actions in the fan - made stories.
The other members like Wendy would look up to Natsu even more in fanfiction scenarios where he shows great power or courage. Makarov, the guild master, would probably shake his head at some of Natsu's more outlandish fanfiction antics but also be glad that Natsu represents the guild's spirit of adventure and loyalty in those stories.
Well, some might be amused. Lucy would probably be both exasperated and fond, as in fanfiction Natsu could get into even wilder antics. Gray might be competitive, thinking Natsu is getting too much attention. Erza would be strict but also secretly proud of Natsu's adventures in the fan - created stories.
Well, first of all, Natsu would probably be excited to see himself in all kinds of wild adventures in the fanfiction. He loves action and if the fanfic has him in some epic battles, he'd be all for it. Lucy might be a bit more critical. She'd look at how she's portrayed in terms of her intelligence and her relationships with the other guild members. Gray would likely be cool about it, but might get a bit annoyed if the fanfic made him seem too cold or too goofy. And Erza would be very strict in her assessment. If the fanfic doesn't adhere to the values of the guild she holds so dear, she might not be too happy about it.
The guild members' reactions would vary greatly. Happy, being Natsu's closest companion, would likely be excited about the fanfiction. He might fly around the guild hall, telling everyone about it and adding his own little comments about how accurate or inaccurate it is. He would definitely be protective of Natsu's image in the fanfiction, especially if it's not a positive portrayal.
The reactions would be mixed. Some of the younger members might be a bit in awe and look up to Natsu and Erza even more. However, there could be some concerns too. For example, some might worry that having a baby will make Natsu and Erza less focused on protecting the guild. But overall, the love and unity in Fairy Tail would likely lead to a positive atmosphere of support for the couple.
Some characters might be shocked. Gray, for example, would probably be really surprised at first. Then the guild as a whole would likely rally around them, offering support. Happy would be excited to be an 'uncle' of sorts.
Most of the Fairy Tail members would not take it well. Happy, Natsu's closest friend, would be extremely confused and sad. He'd follow Natsu around, trying to get him to come back to the guild. Makarov, the guild master, would see it as a huge threat to the guild's safety. He might send some of the stronger members to keep an eye on Natsu and Zeref. And the younger members like Wendy would look up to Natsu so much that they'd be very disappointed and scared for him, thinking that he's making a big mistake by joining Zeref.
Some MHA characters might be really intrigued. For example, Izuku would probably study the magic systems in Fairy Tail fanfiction with great enthusiasm, seeing it as a new form of 'quirks' in a way. He'd be taking notes and trying to understand how the characters use their magic powers for good.
They might be really intrigued. Ruby, being the adventure - loving type, would probably be excited to see the magical and action - packed stories in Fairy Tail fanfiction. Weiss might be a bit critical at first, but could come to appreciate the creativity. Blake would be interested in the different characters' backstories, and Yang would enjoy the battles and the strong - willed characters.
Erza would take charge. She'd make sure the guild was a safe environment for Lucy. She might set up special security measures. Gray would be a bit awkward at first but then become really supportive. He'd probably offer to help with any heavy lifting or practical tasks. The other members would also chip in, like Cana might offer some advice based on her own knowledge, and Levy would help Lucy research about pregnancy in the magical world.
In a fanfiction, other Fairy Tail members' reactions could be complex. Elfman might struggle with his idea of 'manliness' and what this relationship means in that context. Levy would likely be excited for her friends and start looking for more fanfiction ideas based on this new development. Jet and Droy would be more on the side of just following Levy's lead. Juvia, who has her own strong feelings for Gray, might initially be a bit envious but then realize that everyone has the right to love in their own way and become more accepting.