The main character could be an original character with a special doujutsu. For the harem part, characters like Sakura, Hinata, and Ino could be part of it. Sakura with her strong medical and combat skills, Hinata with her gentle yet powerful Byakugan abilities, and Ino with her mind - control jutsu would make for an interesting dynamic around the main character with the doujutsu.
Perhaps the story could be about a ninja who inherits a powerful doujutsu that has some sort of connection to the female characters in Naruto. As he tries to master this doujutsu, these female characters are drawn to him. They end up training together, and during their training, they discover secrets about the doujutsu and their own pasts. This could lead to a series of exciting adventures and the development of deep relationships among them.
Well, in some fanfics, he might obtain them through some ancient ninja magic. Maybe he discovers a hidden scroll or a long - lost temple that grants him the power of all doujutsu.
One interesting story could be about a character who discovers a new godlike doujutsu and as a result, attracts a harem of various Naruto characters. This doujutsu might give him unique powers that make him stand out in the Naruto universe.
The 'naruto doujutsu fanfic' is interesting because it allows for a lot of creativity. Doujutsu in the Naruto series are already very cool, and in fanfics, authors can create new types, powers, and backstories for them. For example, they can explore what would happen if a character had a doujutsu that could control time. It also gives a chance to expand on the existing Naruto world and characters, like seeing how Naruto or Sasuke would react to a new doujutsu user.
One implication is that he becomes extremely powerful. He would be able to see things others can't, predict attacks more accurately, and have a greater variety of combat techniques at his disposal.
First, know the Naruto universe well. Understand the existing doujutsu and how they work. Then, create a unique godlike doujutsu. For the harem part, develop interesting relationships between the main character and the harem members. For example, make them meet in different situations related to the doujutsu.
Another might be the Byakugan. It gives a wide - range view and can see the chakra points in the body. In fanfiction, new and unique abilities of these doujutsu can be explored. For example, the author might create a situation where the Sharingan can not only copy physical techniques but also mental jutsus.
One possible doujutsu could be a time - manipulating doujutsu. It allows the user to slow down or speed up time in a small area, giving them an edge in battles. Another could be a soul - reading doujutsu, which enables the user to see the true intentions and past experiences of others by looking into their souls.
One great 'naruto doujutsu fanfic' is 'The Doujutsu's Ascent'. It focuses on a character developing a new and powerful doujutsu ability. Another one is 'Doujutsu Unleashed' which has amazing battles involving different doujutsu users. And 'Mysteries of the Doujutsu' is also a good read as it delves deep into the lore behind the doujutsu in the Naruto universe.