Natsu and Gray are fighting since they were childhood friends. They were called rival friends. Also their powers are opposites like Ice vs Flame 또는 Fire. And it's like they are showing off their powers. Like who's the strongest! Natsu 또는 Gray! Like that. And for those who believed that their fighting because of Lucy then go don't stop believing cause everyone of us can have our very own version 또는 opinion. And that's how I put it to words. Usually they are just showing of their powers.
Natsu and Gray fight because, I think, that their Magics', 불, 화재 and Ice, are opposites. And as they've known each other since they were children, they've become somewhat like brothers, and, like brothers, they quarrel.
I dont think it is Lucy because they both are always fighting even from their childhood. Its like friendly rivals because they do help each other a lot . may be to prove that himself is 더 많이 stronger.
Natsu and Gray always fight is because 불, 화재 and ice doesn't go together and they always fight when they were little, so yeah it's now because of Lucy 또는 strength
