The most immediate consequence would be the reaction from Naruto's friends. Sasuke, for example, would likely go on a quest for revenge. He has a deep bond with Naruto and would not let his death go unpunished. Sakura would also be devastated and might lose faith in the idea of peace between the villages.
In a possible fanfiction scenario where Naruto is killed by Gaara, it could be due to a breakdown in their understanding. Maybe a powerful and dark force has corrupted Gaara's mind, making him see Naruto as an enemy when Naruto tries to help. Gaara's sand powers are extremely strong and if he goes on a rampage without realizing who Naruto really is, he could end up killing him.
They're similar in their tenacity. Naruto never gives up, no matter how tough the situation is. He keeps fighting against powerful enemies like Pain or Sasuke. Gaara is the same. He has faced numerous challenges, especially when dealing with the internal and external threats to his village. Despite his past traumas, he stands firm. Also, they both understand the pain of being an outcast, which makes them empathetic towards others who are suffering.
Well, Naruto could be depicted as being similar to Gaara in their inner strength. Gaara was always strong on the outside but had a fragile heart. Naruto, in this fanfiction, may share that same duality. Maybe he shows Gaara that having a strong will doesn't mean suppressing emotions. He could be the one to show Gaara that it's okay to let others in, since Naruto is always about making friends and bringing out the best in people.
It could be Orochimaru. He's always been after Naruto for his special powers. He might set a trap for Naruto, but Gaara intervenes and saves him. Orochimaru's motives of immortality and his dark jutsu make him a great antagonist for this kind of story.
At first, their relationship might be a bit guarded. Gaara, being used to isolation, might be hesitant to open up to Naruto. But as they face challenges together, like fighting a common enemy, they would start to respect each other's strength. Naruto's positive attitude would gradually break down Gaara's walls, and they would become friends.
For Naruto, he could develop a deeper understanding of the pain that Gaara has been through. This might make him more empathetic towards others who seem hostile at first. He might also learn new combat techniques from observing Gaara's use of sand in the heat of the Chunin Exams battles.
Well, clearly Naruto and Gaara are the main characters. Naruto is the energetic and determined shinobi from Konoha, always looking to protect his friends and village. Gaara, on the other hand, is the once - lonely and feared Kazekage of Suna, who has a troubled past but has grown into a strong and respected leader.