Well, a major theme is the struggle between light and dark within characters. In this type of fanfiction, Naruto or other characters might be constantly battling their inner demons as they are tempted by the dark slayer powers. There's also the theme of redemption. Some characters who have fallen to the dark side might try to find their way back, and this journey of self - discovery and redemption is a big part of it. And of course, power - hungry antagonists are common, those who seek the dark slayer powers for their own evil purposes.
The themes usually include power corruption. In Naruto Dark Slayer style fanfiction, the powerful dark slayer abilities can easily corrupt those who possess them. This can lead to characters making morally ambiguous decisions. Another theme is the underdog's fight. Just like in the original Naruto, but with a darker twist. A character who is not initially strong might be drawn to the dark slayer powers in order to gain the strength to fight against powerful enemies. And there's often the theme of secrecy, as the use of dark slayer powers is likely to be frowned upon in the Naruto world.
Another theme is the exploration of new worlds. Since dragons are often associated with different realms, Naruto may find himself in strange new places in these fanfictions. This allows for new adventures and encounters with different creatures and characters. It also gives a chance to expand on Naruto's character as he has to adapt to these new situations. For example, he might have to learn the ways of the new world in order to defeat the dragons, which could involve making new alliances or facing new enemies.
One common theme is the combination of powers. Naruto's ninja powers are merged with devil slayer abilities in many fanfictions. For example, he might use his Rasengan with a devil slayer's fire - based attack.
One common theme is power - up. Naruto gets new abilities related to dragon slaying. Another could be friendship, like how Naruto's relationships change when he enters the dragon slayer world.
Another theme is self - discovery. As Naruto faces his dark side, he often learns more about his true nature, his powers, and his place in the ninja world. It's like a journey of self - exploration but with a dark and dangerous twist.
One common theme is power - up. Naruto or other characters often gain new and extraordinary powers related to god - slaying. Another theme is the clash between different power systems, like the ninja chakra system and the god - slaying powers.
A common theme is power acquisition and mastery. The character with sun dragon slayer powers has to learn to control and use them effectively in the Naruto world. Another theme is friendship, like forming bonds with Naruto and his friends.
One of the common themes is the struggle against new enemies. When Naruto becomes a flame god slayer, he attracts the attention of powerful foes who are either after his powers or see him as a threat. Also, friendship and loyalty are themes. His friends in the Leaf Village may be initially skeptical or worried about his new powers, but they still stand by him, and Naruto has to prove that he can be trusted with such great power. This is often shown through various story arcs where Naruto has to make difficult choices to protect his friends while using his flame god slayer abilities.
One common theme is power combination. Writers often explore how Naruto's jutsu can be combined with the fire dragon slayer's abilities. Another theme is friendship, like Naruto making new friends from the fire dragon slayer world. Also, there's the theme of facing new and stronger enemies together.
Well, Naruto is no doubt a top choice. He has a huge fan base already, and in Dark Slayer style fanfiction, fans are interested in seeing how he would handle the new and dangerous dark powers. Sasuke is another one. He has always been on the edge between light and dark, so it's natural for him to be a central figure in these stories. Then there's Orochimaru. His obsession with power and his dark experiments make him a very fitting character for Naruto Dark Slayer style fanfiction. He can be either the main villain or a source of the dark powers that others are after.
Power corruption is also a big theme. His new hanyou powers in the 'dark' concept can be very strong, and there's often a temptation for Naruto to use them in ways that might not be ethical. This leads to internal conflicts within him as he battles between his good side and the darker impulses that come with his hanyou nature.