This was devastating.
First Aang's uncertainty earlier, his desperation at not knowing what he was supposed to do. For all the power he'd displayed, all the enemies he'd taken down in seconds, Aang was just a kid who had a bigger job than anyone in the world.
Now he stood, facing down a spirit monster bigger and stronger than he was, and still not wanting to fight. Maybe he was just a kid, but he was the bravest person Sokka knew.
"That's it!" He couldn't keep it inside anymore. "He needs help!"
And, not listening to anyone else, he ran.
Anyone else think it was ridiculously sweet when Sokka ran in to help Aang despite having no bending and being infinitely less powerful?