His reluctance to be the avatar also he doesn't take his bending training seriously. I understand he's 12 but I feel like he never really took his training seriously like he knows ozai is going to take over the world with sozin comet and when he gets to the north pole he's still slacking around like there's not a ticking time clock.

His lack of commitment to his duties. aang routinely choses his own personal life over his duties as the avatar (which are infinitely more important) and he often avoids problems concerning it even in the final season.

• Aang refusing to talk about his firebending teacher

• Aang wanting to wait to fight ozai

• Aang rather taking trips than going to the north pole

In aang defense about the trips he didn't know the severity of the situation until the 7th episode and after that they still didn't know where they were going so everywhere after that were just rest stops on their way to the pole

Guys I understand that Aang’s biggest fault is running away but I think blaming him for running away from all his problems is severe, like besides in the awakening he really doesn’t run away from anything

I will say what most people say, i.e. his childish running away from his responsibilities. I understand that Aang is (biologically) young, and until episode eight he didn't even know about Sozin's Comet, and of course they had to make some stops on the way to the North Pole, but then he continued to run away from his duties for various reasons.

Probably letting his people die

@DANNY PHANTOM1010 true, he didn't know about their time limit

But at that time he still knew that they were taking over villages, taxing them heavily, killing people en masse and that this had been going on for a hundred years with no end.

That's true still hard to defend but a slight defense

Especially since it was on nickelodeon they kinda had to write it that way to avoid making the situation to depressing for kids

Never listen to Jeong Jeong and accidentally burned Katara with firebending.