In the Southern Water Tribe, family is everything. It's what keeps the village running, what got it through the Fire Nation Raid, and there are few jobs there that could have been done if the villagers didn't fully trust in each other like they did.
The villagers, though not all related by blood, relied on each other.
They trusted each other with their lives everyday.
They fought for each other when ever they had to and for however long they had to.
They were all a family and family didn't leave each other.
That's what Sokka told himself everyday when he woke up; cold, hungry, sore, and scared to the point where he expected his heart to just give out on him. It hadn't yet but he was sure that it was just a matter of time before it stopped beating. There was only so much that a simple water-tribe boy could take and, though he would never tell any of the others this, he was pretty sure that he had just about reached his limit.
Unlike the others, all of them master benders, he just had his wits to rely on. His wits and his sword and his boomerang and his own two legs. He didn't have any fancy bending, he had never been trained to fight, he had never wanted to kill anything bigger than a baby polarbear-dog or a tiger seal.
Everyone else, in his group and the people that he was fighting against, did. They had fire and water and earth and freaking lightening that they could summon and bend to their will.
He had a boomerang and a sword. Sure, his sword was made out of a space-rock and yeah, his boomerang always came back to him, but that wasn't an advantage over anyone. It didn't even bring him up to par with the weakest of fire-benders.
Sokka had been given the choice and the chance to go back, to turn with his tail between his legs and run back to his village, more than once. In the beggining everyone was aware of the fact that he couldn't bend, could barely fight, but as time went by the worried glances and harried 'you okay's stopped.
They realized that he wasn't going to leave them, and as the war expanded, they stopped wasting their time with pointless efforts. He didn't really mind, even if they only thought he was staying for pride, because he knew the truth.
He knew, even now was the black and red clad soldiers moved closer to the cave that the others had already run into, that they were his family.
He knew, even as he threw his boomerang and tightened the grip on his sword, that he trusted them with everything he had.
He knew, even as blood splashed onto his clothes -both his and his enemies- and into the ground at his feet, that he'd keep fighting for them even when his heart was beating out its last march.
He knew, that even though he'd never been trained and even though he didn't have any magic-powers and they all did, that he wasn't about to leave them.
Even if it killed him.
After all, he was a Southern Water Tribe boy and they were the only family that he had left.