A third possible plot development could be the exploration of family values. Naruto, having grown up longing for a family, would be very committed to building a good family environment for Mordred. This could involve teaching Mordred about love, trust, and the importance of family bonds. Mordred, who may not have had such a positive family experience before, would then have to learn and grow in this new family setting. There could also be moments where Mordred has to defend Naruto or their family from external threats, which would strengthen their bond further.
Well, in fanfics, anything can happen. Maybe it's some kind of magic or alternate universe thing that makes Naruto end up as Mordred's father. It could be that a powerful wizard or some strange force manipulated events to bring them together in this unexpected family relationship.
A possible plot development is that Naruto's study of chakra helps him master a new and powerful jutsu. For instance, he might develop a jutsu that can disrupt an opponent's chakra flow from a long distance. This would give him an edge in battles.
One possible plot development could be Naruto leaving due to a misunderstanding. For example, if he is wrongly accused of a crime within the team. Another could be that he feels he is holding the team back in some way and decides to leave on his own to become stronger alone. Maybe he has a personal goal that he believes he can't achieve while still being part of Team 7.
One possible plot development could be that Naruto uses Kirin to surprise his enemies. Since it's not a jutsu associated with him usually, it would catch his foes off - guard.
One possible plot development could be the initial shock and adjustment for both Naruto and Mei. They would have to deal with the reactions of their respective villages. Naruto's friends in Konoha might be surprised, and Mei's allies in Kirigakure would also have their thoughts.
One possible plot development is that Nagato and Naruto form an alliance to take on a new, greater threat. This threat could be an ancient evil that requires both Nagato's power and Naruto's spirit. Another development could be Nagato using his abilities to help Naruto unlock new powers or forms. For example, he might help Naruto better understand the Sage of Six Paths' power within him.
One possible plot development could be Naruto's ideals getting warped due to some traumatic event. For example, if he fails to save a dear friend, he might start to believe that the only way to achieve true peace is through extreme force. Another development could be his relationships turning sour. Maybe his friends start to fear his new, twisted self and Naruto, feeling betrayed, becomes even more deviated from his original self. Also, his view of the ninja world could change completely, seeing it as a place that needs to be remade in his own image rather than following the traditional ways.
One possible plot development is that Naruto becomes a target. Since Hashirama cells are very valuable, many villains might try to capture him to study or use the cells for their own evil purposes. Another is that he has to learn to control the new power from the cells. It could be a struggle at first, and he might accidentally cause some destruction while trying to master it.
In the fanfic, Naruto may learn of his heritage through a new character. Maybe a mysterious ninja shows up who has some connection to his family. This ninja could start to train Naruto in ways that are specific to his family's ninja techniques, revealing more about his heritage as they train together.
One possible plot development could be that Sasuke is in a life - threatening situation, perhaps against an extremely powerful enemy. Naruto sacrifices himself to give Sasuke a chance to escape or defeat the foe. This would likely lead to Sasuke being filled with guilt and regret, and might change his whole outlook on life.