She might start to blush furiously. Given her character, she is a bit shy when it comes to romantic matters. And then she might start to stammer out a response, not really sure what to say at first. As she composes herself, she could tell Natsu that she has feelings for him too but in a very gentle and sincere way.
Lucy might be heartbroken. After all, Team Natsu was like a family to her. She could initially go into a state of shock and disbelief. Maybe she would try to plead with the team to let her back in, explaining that whatever they thought she did was a misunderstanding.
Erza would probably be very protective. She would make sure Lucy has everything she needs and would be strict about her safety. Gray might be a bit awkward at first, but then he'd be supportive. Happy would be over the moon. He'd constantly be around Lucy, bringing her fish and trying to cheer her up. Wendy would be excited and would offer to use her healing magic to check on the baby's health regularly.
Their friends would likely be shocked at first. Happy for them, but also a bit worried. Erza, for example, would probably be very protective. She might start giving Lucy all sorts of advice on staying healthy and safe during the pregnancy. Gray might be a bit awkward around the whole situation at first, but would eventually warm up and offer his support in his own way, like helping Natsu with any odd jobs or tasks so he can focus on Lucy.
First, know the original characters well. For example, if you're writing about Gray, remember his cool - headed nature and his habit of stripping. Then, come up with an original plot. It could be a new adventure in a different part of the Fairy Tail world.
I really like 'The Lost Guild'. In this fanfiction, the Fairy Tail guild is in a crisis when a powerful dark guild tries to steal their most precious artifact. It's full of action and the relationships between the characters are really well - written, like the friendship between Lucy and Erza.
The number of chapters in the FairyTail manga is quite substantial. It's around 500-plus. The manga keeps you engaged with its many plot twists and developments throughout these chapters.
Some fans would be really excited. They might love the idea of seeing their favorite characters in a more mature and family - oriented situation. It could add a new dimension to the Natsu - Lucy relationship that they've always wanted to see.
Their friends would probably be really excited. Natsu might be a bit over - enthusiastic, constantly wanting to play with the baby and accidentally scaring it at first. Erza would be very helpful, giving advice on how to raise a strong and independent child. Happy would be curious and might offer to babysit in his own unique way.