A common plot element is Naruto initially stumbling upon the ability to absorb bloodlines, often by accident. For example, it could be during a fight or while exploring an ancient ruin.
Another good one is 'Absorbing Bloodlines: Naruto's New Path'. This fanfic focuses on Naruto's journey as he absorbs various bloodlines and how it affects his relationships with his friends and foes alike. The author does a great job of exploring the moral implications of Naruto having such a powerful ability, and it has some really cool action scenes.
In this fanfiction, the Sharingan from the Uchiha clan is an obvious choice. It has so many abilities like the ability to copy jutsu and predict movements. Naruto could become even more of a prodigy if he absorbs it. Also, the Aburame clan's ability to control bugs could be quite interesting. Naruto could use bugs for reconnaissance or even in combat in ways that are different from his normal fighting style. And the Inuzuka clan's connection with animals, if Naruto could absorb that bloodline, he might be able to form a stronger bond with his summons or other animals in the wild.
Well, it could change the power balance significantly. If Naruto can absorb bloodlines, he might gain new and unique abilities. For example, he could absorb the Sharingan's power, which would give him enhanced visual abilities and maybe even some of the Uchiha clan's signature jutsu. This would make him an even more formidable opponent and could change the way battles play out. It might also create new rivalries or alliances as other characters react to his newfound powers.
Well, it could be that in this fanfic, Naruto has developed a new jutsu that allows him to analyze and then replicate the DNA - like aspects of bloodlines. He might be using his vast chakra reserves to fuel this ability. For example, if he encounters a bloodline with a special element - like the Ice Release of the Yuki clan - he could break down the chakra signature and recreate it within himself.
One possible fanfic could be about a world where Naruto's chakra bloodline and Spiderman's radioactive - spider - bitten bloodline somehow get combined. Maybe a scientist in a multiverse experiment goes wrong and mixes the genetic elements of the two. This could lead to a new hero or anti - hero with the agility and web - slinging ability of Spiderman and the chakra - based powers like ninjutsu from Naruto.
If Naruto absorbs the Juubi in fanfic, it could change the whole Naruto universe in that story. He may have new forms or abilities. Maybe he could use the Juubi's power to bring peace to the ninja world more quickly. He could also face new challenges as other characters might fear his new - found power.
If Naruto absorbs Kaguya in a fanfic, it might lead to a very different storyline. He could use Kaguya's power to bring about a new era of peace more quickly. For example, he might be able to use her power to stop all forms of aggression instantly. Also, his appearance might change slightly, taking on some of Kaguya's physical traits. And his understanding of the chakra and the world's origin could be greatly enhanced.
One implication is that Naruto's power level would skyrocket. He would be much stronger than before and could potentially change the power balance in the ninja world.
Maybe he uses some kind of special jutsu. It could be a new form of his shadow clone jutsu where the clones are able to analyze and then copy the bloodline traits of the opponents they encounter.