One possible plot could be that Naruto has faced so many betrayals. Maybe his friends turn on him due to some false accusations. This shatters his warm - hearted nature, and he becomes cold as a defense mechanism. He starts to isolate himself and no longer trusts easily.
One possibility is that Naruto might feel a sense of isolation. Since Sasuke has achieved the highest position in the village, Naruto might feel like his own journey and achievements are overshadowed. He could become cold as he withdraws into himself, thinking that he no longer has a clear purpose in the village where his best friend now holds all the power.
If Naruto becomes cold, his relationship with Hinata would be severely affected. Hinata, who loves him for his warm heart, might be at a loss. Naruto might start to push her away, not allowing her to get close. His friends from Team 7 might try to bring back the old Naruto, but his coldness would create a rift between them.
Naruto could become cold due to disappointment. He might have expected Sasuke to rule in a certain way, but when Sasuke becomes Hokage and starts making decisions that seem contrary to Naruto's ideals, Naruto feels let down. This disappointment could turn him cold towards Sasuke and the village in general.
Most Naruto fanfics tend to focus on his adventures, his relationships in a positive way, like his bond with Sasuke or his training with Kakashi. The idea of Naruto becoming a pervert is quite out of the ordinary for the Naruto - themed fanfic world. It's not something that is typically explored in mainstream Naruto fan creations.
One possible plot could be that Naruto experiences a great betrayal, perhaps by someone he deeply trusted in the village. This could make him lose faith in the bonds he once cherished and become cold towards others. He might start to isolate himself and focus only on his own power, believing that relying on others will only lead to more pain.
His relationship with Sakura would definitely be affected. Sakura, who has always known the warm - hearted Naruto, would be shocked and confused. She might try to reach out to him at first, but if he keeps pushing her away, she could become frustrated or even give up. Their friendship would be strained.
Maybe Percy has been through a great betrayal, like his closest friend turned on him for power. So he starts to close off his emotions to avoid being hurt again.
One idea could be that Naruto's greed is for power. He might see all the strong shinobi in the Hidden Leaf and start to envy their abilities, so he becomes greedy for more power. He could start seeking out forbidden jutsu or training methods that are considered dangerous.
In some fanfics, Naruto might be depicted as cold - hearted, but it goes against his canonical character. The original Naruto is known for his warm - heartedness, determination, and his ability to see the good in people. Fanfic authors may take creative liberties for various reasons like exploring different storylines or character arcs, but it's not a common or true - to - the - source representation of Naruto.