Mentally, the curse mark can be a huge burden. Sasuke could become more isolated and brooding as the curse mark feeds on his negative emotions. Naruto, being the optimist, tries to break through to Sasuke. He might become more determined and grow in his understanding of Sasuke's pain. In some fanfictions, this could lead to Naruto sacrificing some of his own energy to suppress Sasuke's curse mark, which changes their dynamic even more.
The curse mark can change their physical abilities. For Sasuke, it might enhance his speed and strength, but also make him more prone to losing control. Naruto, on the other hand, might develop new chakra - related powers because of his exposure to Sasuke's curse mark. For example, he could gain the ability to sense the curse mark's energy better.
In some fanfictions, the curse mark can initially drive a wedge between Naruto and Sasuke. Sasuke might become more withdrawn and brooding due to the power and dark influence of the curse mark. Naruto, on the other hand, would be worried about his friend but might not fully understand what Sasuke is going through. This could lead to some misunderstandings and arguments between them as Naruto tries to reach out while Sasuke pushes him away.
The curse mark could make Naruto more cautious. Since it's a dangerous and unpredictable power, he might think twice before acting impulsively as he usually does. For instance, in battle, instead of rushing in head - first, he'll consider the consequences of using the curse mark's power.
After absorbing the curse mark, Naruto's character development could take a significant turn. Firstly, he may face new challenges in controlling his emotions as the curse mark might have an impact on his temperament. He could become more impulsive or aggressive in battle. However, this also gives him an opportunity to grow. He has to learn to harness this new power without succumbing to its negative effects. It could lead to a more mature Naruto as he grapples with this new aspect of himself.
One interesting plot could be how the curse mark affects their relationship. Maybe Sasuke's curse mark starts to make him more aggressive towards Naruto, but Naruto is determined to save him from its dark influence. This could lead to some intense battles and emotional moments between them.
Their friends might be initially afraid of them. Since the curse mark is often associated with dark power, friends like Sakura and Kakashi could be worried that Naruto and Sasuke might lose control. This could create some distance between them as their friends are not sure how to approach them anymore.
Naruto's relationship with Sasuke could be really affected. Sasuke, having his own experiences with dark powers, might see Naruto in a new light. They could either become more competitive as they both struggle with different forms of dark power, or they could bond over their shared experiences of having something that sets them apart from others.
In some fanfictions, the curse mark can be a source of tension. If Sasuke's curse mark makes him more aggressive or unpredictable, Sakura might be worried about him. For example, he could accidentally lash out at her during a training session. This would put a strain on their relationship as she tries to help him and he tries to keep his distance to protect her from the curse mark's influence.
The curse mark in the fanfiction could be a catalyst for fem Naruto's growth. It could bring out hidden aspects of her personality. Maybe it gives her access to new powers that she has to learn to control. This process of learning and the physical and mental changes caused by the mark would surely have a profound impact on her character development. She might become more cautious, as she realizes the potential danger of the mark, yet also more bold in her attempts to master it.
The curse mark could have a mind of its own. It starts to communicate with Naruto and Sasuke in their dreams, trying to manipulate them into doing its bidding. Naruto, being the optimistic one, tries to resist and turn the curse mark's power into something positive. Sasuke, however, is more tempted by the power it offers. This could lead to a rift between them as they have different approaches to dealing with the curse mark, and their relationship would be put to the test.
One possible plot could be that they get the curse marks from a new, powerful enemy. They then have to figure out how to control the curse marks together without losing themselves to the dark power. Maybe they go on a journey to find a way to remove the marks while also facing challenges from other villages who see them as a threat because of the marks.