In fanfiction, Naruto could be depressed after the war because he realizes that the world he fought for is still full of problems. The shinobi system might still be corrupt in some ways, and he may feel that all his efforts haven't really changed the fundamental issues. He might also be suffering from post - war stress disorder, constantly reliving the battles and the horrors he witnessed.
Well, Naruto might be depressed because of the changes in his relationships. Some of his friends might have changed a great deal during the war. For example, Sasuke. Even though they reconciled, there could be underlying tensions or differences that Naruto can't ignore. Also, the expectations of the village on him could be overwhelming. He has to be this perfect Hokage figure, but he is still a human with his own emotional turmoil.
One reason could be his sense of isolation. In many fanfictions, Merlin might feel alone as he has to keep his magic a secret from most people around him. This constant hiding and fear of discovery can lead to depression.
Well, it could be due to the weight of expectations. Naruto is often seen as the 'chosen one' type of character. In fanfic, Sasuke might feel pressured by this. He might think that no matter what he does, he'll always be in Naruto's shadow. Also, their different upbringings play a role. Naruto grew up alone but with a positive attitude, while Sasuke had a tragic family past. In fanfic, seeing Naruto's strength despite his hardships could make Sasuke question his own strength and lead to depression.
One reason could be that Gaara, being a powerful and complex character, might have a different view on the concept of friendship. If he were to tell Naruto that his friends are only with him out of obligation or because of his status as a hero, Naruto might start to doubt his relationships and become depressed.
Another reason could be related to the trauma he experienced during the war. Naruto witnessed a great deal of death and destruction. Staying in Konoha might constantly remind him of the horrors he faced. By leaving, he hopes to escape those memories at least for a while and find some peace. He may also believe that his presence in the village is a constant reminder of the war to the villagers, and he doesn't want to be a source of their pain.
It could also be that Harry himself is so traumatized by the war that he isolates himself. He might push people away, thinking that he's a danger to them. As he withdraws, others might misinterpret it as him not wanting their company and gradually abandon him.
One possible reason could be that he is framed for a crime he didn't commit. Maybe someone with a vendetta against him planted false evidence to make it seem like he attacked a village or something similar.
Perhaps in the fanfiction, Naruto is tired because he is constantly traveling. He might be on a long - distance mission to gather information or allies, and the journey itself is exhausting. He could also be tired due to a lack of proper rest. Fanfiction writers might depict him as being so dedicated to his tasks that he neglects to take breaks, leading to fatigue. Or it could be that he is using too much of his chakra in experimental or new jutsu that he is trying to master in the fan - made stories, which leaves him drained.
It could also be related to his unfulfilled dreams. Naruto has big dreams for the village and for peace. But as he progresses, he might realize that achieving true peace is far more difficult than he thought. The gap between his ideals and the reality might be leading to his secret depression.
One possible reason could be jealousy. Maybe some of his former allies were envious of his fame and hero status. Another reason might be political manipulation. There could be those who wanted to use his downfall for their own gain in the post - war wizarding world.
In some cases, the fanfiction might be a crossover with another universe where the idea of a ninja doesn't fit. So, to make Naruto fit into this new universe, the writer has to take away his ninja identity. This allows for new and interesting interactions between Naruto and characters from the other universe.