The consequence might also be a shift in the balance of power in the Naruto universe. With all that chakra, Naruto could potentially change the political situation. He could end wars single - handedly or force the different ninja villages to re - evaluate their strategies. Moreover, his own physical and mental state might be affected. There could be a struggle within him to keep his identity intact while dealing with such an overwhelming power source.
Perhaps there is an ancient artifact or a powerful curse that causes Naruto to absorb all chakra. In the fanfiction world, it's common to introduce such unique elements. For example, he might find a magical scroll that, when opened, starts sucking in all the chakra in the vicinity and then channels it into Naruto. Or it could be a curse placed on him by an enemy, but instead of harming him, it gives him this strange power to absorb all chakra.
One interesting way is when Naruto absorbs chakra through his shadow clones. In some fanfictions, the clones can be used not just to gather information or attack, but also to absorb the chakra of the opponents they interact with. Then, they transfer this absorbed chakra back to Naruto, making him more powerful.
Well, it depends on the source of the Chakra he absorbs. If it's from a powerful and dark entity in the fanfiction, Naruto might struggle with the corrupting influence of that Chakra. He'd have to find a way to purify it or control it, which could be a major part of the story arc. It could also potentially change his personality a bit, making him more brooding or serious as he tries to deal with this new power.
One consequence could be that he becomes extremely powerful. His physical abilities like strength, speed, and endurance are enhanced. He can also use more powerful jutsus with the extra chakra boost from the Kyuubi.
Some fanfictions have Naruto absorb chakra from natural disasters. For instance, he can draw chakra from a lightning storm or a volcanic eruption. This is really creative as it ties his power to the forces of nature.
He might gain an enormous boost in his chakra reserves. This could make his jutsus much more powerful and enable him to perform complex techniques with ease.
In some fanfictions, controlling the Kyuubi chakra might change Naruto's appearance. He could have some physical features related to the Kyuubi, like red - tinted eyes or a more ferocious look when using the chakra. Also, his relationships with others might be affected. Some might be in awe of his new power, while others could be afraid of him.
In some fanfictions, Naruto absorbs the chakra of a mythical creature. For example, he absorbs the chakra of a Phoenix. This chakra not only enhances his physical abilities but also gives him the power of regeneration. As a result, he becomes almost invincible in combat, being able to heal from any wound quickly.
Well, one consequence could be that his ability to perform jutsus is severely hampered. Since chakra coils are crucial for chakra flow, damaged ones might lead to erratic or weak chakra output, making it difficult for him to execute even basic techniques properly.
Naruto might also go through an identity crisis. His whole life has been centered around being a ninja with chakra and using powerful jutsu. Losing his chakra could make him question who he is and what his purpose is. He would have to redefine himself and find a new way to contribute to the ninja world. This could be a long and difficult process for him.