In their married life, Natsu and Yukino would likely support each other's growth as mages. Natsu could teach Yukino some of his more unorthodox combat techniques, and Yukino could introduce Natsu to the more refined aspects of Celestial Spirit magic. They might have to keep their marriage a secret from the general public for a while, which would add an element of mystery and excitement. At night, they could sit under the stars and talk about their dreams for the future, whether it's about making their respective guilds stronger or just having a family of their own one day.
Well, their married life might be full of adventures. Natsu, being his energetic self, would probably take Yukino on wild dragon - slaying quests. They could discover new magical places together. And at home, Yukino would keep things organized while Natsu might accidentally break a few things in his exuberance. They'd also have to deal with their different guilds and friends' reactions to their secret marriage.
To keep their marriage a secret, they would have had to be very careful. They could have met in secluded places like an abandoned forest or a hidden cave. When communicating with others, they would be extra cautious not to let any hints slip. Natsu might have pretended to be just a friend to Yukino when around others, and Yukino would do the same. They might also have had a secret code or signal to let each other know when it was safe to be together.
Their married life could be full of adventure. Natsu, with his fiery spirit, might bring excitement and spontaneity. Cana, being a strong - willed and fun - loving character, would keep things lively. They could go on quests together, with Natsu leading the way in battles and Cana using her card magic to support. At home, they would probably have a cozy place filled with mementos from their adventures, and they'd often have friends over for parties and celebrations.
Well, their married life could be full of adventures. Natsu being the energetic dragon slayer would probably take Juvia on wild quests. Juvia, on the other hand, would be the loving and supportive wife. She'd use her water magic to help them out in tough situations. For example, if they were in a desert, she could create water for them to drink. And they'd have a cozy home, with Natsu's warm presence and Juvia's tender care.
Their married life would probably be full of adventures. Natsu's fiery nature combined with Erza's strong leadership would make them a dynamic duo. They might go on quests together, with Natsu using his dragon - slaying powers and Erza leading the way with her strategic mind. And at home, Natsu would surely make Erza laugh with his goofy antics while she keeps him in line.
They might face challenges from their respective guilds. Maybe Fairy Tail and Mermaid Heel have some sort of rivalry or rules that could make their marriage a big deal if it was known. So they have to be really careful.
It could be full of drama. Maybe they keep it a secret because of guild rules or some outside threat. For example, they might fear that a rival guild would use their relationship against them.
One reason could be that they want to avoid the chaos that would ensue among their friends and guildmates. Their relationship might be seen as unexpected, and they might fear the constant teasing and interference. For example, some of their more rambunctious friends could make a big fuss and it would disrupt their normal lives within the guild. Also, they could be worried about how their relationship might affect their standing in the guild as strong mages. They may want to keep their relationship private until they are sure it can withstand any potential problems that might come from being public.
Lucy could be a potential spouse. They have a very close relationship in the original story. Maybe they got secretly married in a moment of intense emotion. It would be a big shock to their friends, but also a very interesting development as they already have such a strong bond.
One possible plotline could be that Natsu has been secretly married to a character from his past. Maybe it was a rushed decision during a dangerous adventure, and they kept it a secret to protect each other. As the story unfolds, his friends start to suspect something is different about him. He becomes more cautious and less reckless, which is out of character for him.
Yes, there are likely fanfictions on this topic. The 'Fairy Tail' fandom is quite large and creative, so it's not uncommon for fans to write about such pairings getting married in secret. However, the availability might depend on the specific fanfiction platforms you search on.