I noticed one thing that does seperate Aang from the other animated heros of today. He is very humble. He rarely gives any one liners when fighting villain, he doesn't trash talk. The only time he has ever done such behavior is in episode 117 and he did it as per his strategy.
Ever other young hero in animation today like Danny Phantom, Ben 10, American Dragon: Jake Long, most of the Teen Titans, and even Kim Possible who doesn't have powers actully, they like to flunt their abilities, and do some trash talking along the way.
But I think Aang's humbuleness might be a reason why Aang seems to be very unpopular, a lot of fans think he is boring. I am not one of them, just saying what I have heard. But if Aang could so a little more arrogance and more of sense of humor in battle like the heros I mention above, and for example when fighting Fire Benders say "Hey Fire Bender head, eat my Avatar dust." or something like that, when his comrads tell him to be careful to reply "Please I am the Avatar, this is easy" would it make him more popular among fans?
I know people like these heros I mention above, because they would act arrogant if they had super powers, and maybe they feel more relatable to someone who lets it go to their heads sometimes.
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