In some 'dark natsu nalu fanfiction', the story could be set in an alternate universe where the Fairy Tail guild has fallen. Natsu and Lucy are on the run from a powerful and evil force. They have to rely on each other more than ever. Natsu's fire magic might be dampened in this dark world, and Lucy has to be extra careful with her magic keys as they are constantly being hunted. Their relationship evolves in this difficult situation, with both of them growing stronger together.
One interesting 'dark natsu nalu fanfiction' story could be about Natsu and Lucy facing a powerful dark magic that is corrupting their world. In this story, Natsu's dragon powers are affected in a strange way, and Lucy has to use her celestial magic in innovative ways to save them both.
One interesting Nalu dark fanfiction could be where Natsu is under a dark spell and Lucy has to find a way to break it. In this story, Natsu might be forced to fight against his friends, and Lucy's love for him is put to the ultimate test as she battles not only the external threats but also Natsu's inner darkness.
Another type of 'dark nalu fanfiction' could be set in a world where Natsu loses his memories and becomes a part of a dark guild. Lucy then has to infiltrate the guild to bring him back to his senses. It's full of action, suspense and of course, the underlying relationship between Natsu and Lucy.
You can try looking on fanfiction websites like FanFiction.net or Archive of Our Own (AO3). They have a wide variety of fanfiction, including 'dark natsu nalu' ones. Just use their search functions and type in 'dark natsu nalu' to find relevant stories.
One great Nalu fanfic is 'A New Adventure'. It takes place right after the main story and shows Natsu and Lucy going on a quest that was hinted at in the original series but never fully explored. Another is 'Nalu's Bond', which delves deep into their relationship, showing how they support each other through tough times. There's also 'Fairy Tail: Nalu's Destiny' that has an alternate universe concept where they have different roles in the guild but still end up being drawn to each other.
In some nalu dragon fanfiction, Natsu and Lucy are transported back in time to the era of the dragons. There, they meet Igneel and other dragons in their prime. This encounter not only gives Natsu a chance to learn more about his past and his dragon heritage but also allows Lucy to understand Natsu on a deeper level. They might get involved in a conflict between different dragon clans, and their love for each other becomes a key factor in resolving the situation.
There's 'Destined Hearts'. This fanfiction might explore the idea that Natsu and Lucy are soulmates. Their connection is so strong that it leads to some steamy and loving scenes. It could involve them facing challenges together and their love growing stronger through it all, with the lemons aspect adding a bit of spice to their relationship.
One interesting Nalu Lemon fanfiction could be about Natsu and Lucy going on a secret adventure where their relationship deepens in a romantic way. Maybe they get lost in a magical forest and have to rely on each other, which leads to some tender and passionate moments.
One popular 'natsu is dark fanfiction' might be those that explore Natsu's inner turmoil in a more sinister way. For example, a story could depict him being corrupted by a dark magic that changes his personality. He might become more aggressive towards his friends, not out of true malice but because of the influence of the dark power. This can create a lot of conflict and drama within the Fairy Tail universe.
One of the main themes is family. The addition of a baby in the Natsu - Lucy relationship brings out a whole new aspect of family life. It shows how they support each other as parents.
The contrast. Natsu is known for his hot - tempered and fiery nature. When you introduce a 'cold' element, it creates an immediate contrast. For example, if Natsu is in a cold, icy place, his usual fire - based magic might not work as well, and he has to rely on his inner strength. This struggle makes the story interesting. Also, the relationship between Natsu and Lucy (Nalu) is always a key factor. In a 'cold' situation, they might have to rely on each other more, which deepens their bond and makes the fanfic engaging.