The child might have Natsu's pink hair, but with Lucy's brown eyes. Or perhaps a combination of their features, like pinkish - brown hair.
She would fit in very well. The Fairy Tail guild is all about family and acceptance. Given her parents are Lucy and Natsu, she'd be welcomed with open arms. She could learn from the older members like Makarov and Mirajane, and bond with the younger ones like Romeo. Her magic skills would also contribute to the guild's strength during battles or when helping the town.
One possibility is that their child inherits Natsu's dragon - slayer magic and Lucy's celestial spirit magic. Maybe the child uses this unique combination to protect Fairy Tail from a new, powerful enemy.
Their wedding would be a grand affair. All the Fairy Tail members would be there. Natsu would be in his best suit, looking a bit uncomfortable but happy. Lucy would be in a beautiful white dress, with her Celestial Spirits perhaps helping with the decorations. There would be lots of food, music, and dancing. Gray might accidentally freeze something during the celebration, and Erza would keep everyone in line. It would be a day filled with laughter and joy.
Well, it could be really exciting. Their daughter might inherit Lucy's celestial magic and Natsu's dragon slayer powers. Maybe she'd be on adventures with the new generation of Fairy Tail wizards, facing powerful enemies and making new friends just like her parents did.
In fanfiction, a child of Natsu and Erza might inherit Natsu's fiery temper and love for adventure. They could also have Erza's strong sense of justice and discipline. Maybe they'd have Natsu's pink hair and Erza's beautiful eyes. And they'd probably be a powerful mage, combining Natsu's dragon slayer magic with Erza's requip magic.
He could kidnap her because he believes she's in immediate danger. Natsu is very impulsive and might not have time to explain things properly, so he just takes her away to keep her safe.
The guild would likely be ecstatic. Gray would probably make some snarky comment about Natsu finally growing up, but deep down he'd be happy for his friend. Erza would be all for it and might start planning the wedding immediately, giving orders to everyone in the guild to help out.
The story could focus on their journey to find a new place to belong. They might meet new allies along the way who have different values and magic abilities, which would add new elements to the story. For instance, they could encounter a group of mages who use music as their form of magic.
In many fanfictions, Lucy's love for Natsu is often shown through her unwavering loyalty. She stands by him in battles, always believing in his strength. For example, she might heal his wounds after a tough fight, a simple yet powerful display of her care.
Well, a lot of fanfictions portray Lucy's love for Natsu in a very subtle way. It could be in the little things like how she always makes sure to save a seat for him at the guild or how she blushes slightly when he gets too close. Sometimes, it's also shown through her jealousy when other girls show interest in Natsu.