One common theme is sacrifice. Natsu is willing to put himself in harm's way for the princess, which shows his selfless nature. Another theme could be loyalty, as he is loyal to the princess and to the idea of protecting the innocent. Also, there might be a theme of recovery, as Natsu has to recover from his injuries, which can show his strength and the support he gets from his friends and the princess herself.
One possible plot could be that there is an attack on the kingdom where Princess Hisui resides. Natsu, being the brave character he is, jumps into action. As he battles the invaders, he gets hurt while making sure no harm comes to the princess. Maybe the invaders have some sort of dark magic that Natsu underestimates, and it catches him off - guard, resulting in his injury.
It could be that Natsu underestimates the strength of the final boss guarding Princess Hisui. During the intense battle, he takes several hard hits but refuses to give up. He endures the pain and uses his last bit of strength to defeat the enemy and save the princess.
He might get seriously injured. For example, he could be poisoned by some magical creature protecting the princess. This would make him weak and in pain but still push through to save her.
In these fanfictions, Natsu getting hurt protecting Lucy often deepens their relationship. It shows Natsu's selfless love for Lucy. For example, Lucy might realize how much she means to Natsu and become more protective of him in return. Their bond becomes stronger as they face the aftermath of Natsu's injury together.
One popular 'Natsu Hurt Protecting Lucy' fanfiction might be 'A Protective Flame'. In this fic, Natsu jumps in front of a powerful dark magic spell aimed at Lucy. His selfless act shows his deep care for her. Another could be 'Flame's Sacrifice' where Natsu endures a brutal attack while shielding Lucy from a horde of demons. The angst and the way their relationship is portrayed makes it a great read.
Well, without reading the specific 'natsu and hisui' fanfiction, it's hard to say in detail. But generally, it might be about their relationship, perhaps an adventure they go on together, or how their personalities interact. It could be a story that explores their characters in a new and unique way.
Yes, there might be some out there. You can start by checking fanfiction platforms like FanFiction.net or Archive of Our Own. Just search for 'natsu and hisui secretly married' and you'll likely find several stories. However, the quality can vary greatly, so you may need to read a few to find one that suits your taste.
People like 'natsu and hisui love fanfiction' because it combines two interesting characters. Natsu is a well - loved character with his energetic and brave nature, and Hisui is also an appealing character. Their relationship in fanfiction offers a new perspective on the existing fictional world.
There's also 'Love Beyond Guilds'. It shows how Natsu and Hisui's relationship develops despite being from different guild - related backgrounds. Natsu is from Fairy Tail and Hisui has her own set of responsibilities. But their love manages to bridge those gaps. It's a story full of adventure as they go on quests together and face various challenges that test their relationship.