One popular trope is the merman Naruto having enhanced underwater combat abilities. Since he has the merman bloodline, he can swim at incredible speeds and use water as a weapon more effectively. For example, he might be able to create powerful water currents or whirlpools with just a flick of his tail. Another trope could be the isolation aspect. Naruto, as a merman, might be shunned by some in the ninja world who don't understand his kind. This could lead to a story of him trying to prove his worth and find acceptance among his peers.
The Naruto's merman bloodline can greatly impact his relationships. If we consider his relationship with the village elders, they might see him as a potential threat or an asset depending on how they view his new abilities. They could try to use him for their own purposes, like sending him on dangerous underwater missions. With his peers, some might envy his unique powers, while others could be inspired by him. And when it comes to his family - like relationship with Iruka - Iruka might worry about Naruto being in a world that doesn't fully accept his merman side and try to protect him while also encouraging him to embrace his new identity.
One common theme is identity. Since Naruto is usually a human in the original series, when he becomes a merman in fanfiction, he has to figure out who he is in this new form. Another theme is acceptance, as he may face prejudice from both humans and mermen.
There are also fanfictions where a bloodline is created through some sort of experimental jutsu. For example, a bloodline that allows the user to transform into different elements at will. This would give the character an edge in combat as they could adapt to any situation by changing their form.
There's also 'Naruto: Merman of the Hidden Leaf'. In this fanfic, Naruto is a merman from the start, living in a secret part of the Hidden Leaf village. It has some interesting twists, like how Naruto uses his merman abilities to protect the village in unique ways, which is quite different from the original Naruto plot.
The knight bloodline could be integrated as a foreign power that was brought to the Naruto world long ago. Maybe a group of warriors from another dimension with the knight bloodline came and settled, and over time their bloodline got diluted but still resurfaces in certain individuals.
He might use some special jutsu or seals. For example, he could use a sealing technique to suppress the signs of his bloodline. This way, others wouldn't be able to detect it through normal means like sensing chakra.
It could also be part of a strategic move. By hiding his bloodline, he can surprise his opponents in battle. They would underestimate him based on not knowing about his true powers, and then he could turn the tables on them when the time is right. This gives him an edge in combat situations.
Well, one implication could be enhanced physical abilities. Dragons are often seen as strong and powerful creatures in many mythologies. So Naruto might have greater strength, speed, and endurance. He could also have some sort of elemental control related to dragons, like breathing fire or manipulating wind in a more dragon - like way. Maybe he could even fly in some forms, as dragons are known for their flight ability.
In Naruto fanfiction, the concept of a bacteria bloodline can be really interesting. It could potentially give the character unique abilities. For example, they might be able to control bacteria for various purposes like healing or creating poisons. Some fanfictions may explore how a character with this bloodline is treated in the ninja world, whether they are feared or revered.