One key element is the unique relationship between Natsu and Grey. The lemon aspect often adds a bit of spice or tension to their interactions. For example, it could be a source of banter or a new way for them to understand each other.
In many Fairy Tail fanfictions, the battle between Natsu and Acnologia is often depicted as extremely epic. Natsu's fiery determination and his unique dragon - slayer magic make for an interesting contrast against Acnologia's overwhelming power. Some fanfictions might have Natsu discover new forms or powers in order to stand a chance against the fearsome Acnologia.
Lucy might also be an ally. She has her celestial spirits that could be a great help. For example, some of the spirits like Leo could be very powerful in combat against the dragons. Also, Erza would be a great addition. With her various armors and combat skills, she could hold off a large number of dragons while Natsu focuses on the more powerful ones among the 10000.
The main characters are Natsu and Grey Lemon. Natsu is likely to be a strong - willed and energetic character, while Grey Lemon might have some unique traits that make their relationship interesting.
One common theme might be adventure. Since they are two characters (presumably from some fictional world), their stories could involve going on exciting quests together. Another could be friendship, as they might develop a deep bond through their shared experiences.
Well, perhaps Natsu uses his powerful fire magic to take on the dragons one by one. He might start by finding a strategic location to face them, like on top of a large mountain where he has a better view. Then, he'd use his signature moves like Fire Dragon's Roar to blast groups of dragons at a time.
There's also 'The Unlikely Alliance'. This fanfiction focuses on a situation where Grey and Natsu have to team up against a powerful dark mage. It's really interesting to see how their different magic styles complement each other and how their relationship evolves during the mission.
Some fanfictions in 'natsu x grey lemon' might focus on the theme of family. Maybe they create a family - like bond, or they are dealing with issues related to family. There could also be a theme of redemption, where one of them has made a mistake in the past and is trying to make up for it through their relationship with the other.
One great natsu and grey lemon fanfiction is 'A Unlikely Bond' which shows an interesting dynamic between them. It has a unique plot that keeps you engaged.