ok yes it’s fun to think about atla roleswap AUs where the fire nation is good and the water tribes are bad, but ultimately they wouldn’t really work because if sokka had been on the bad side then the bad guys would have won full stop
like even if we’re assuming just for funnsies that in this au sokka does have a reason go on his own zuko-esque character journey, I would like you to consider how much sokka accomplished when he was spending most of his energy/brainpower desperately trying to keep 3 prodigiously powerful preteens (who, let’s be real, saw him more as an annoying older brother than as a real authority figure) alive and out of trouble.
now please imagine how powerful sokka would be if he had complete authority over a fully staffed warship and its crew. he would have delivered aang to his father by the end of episode 2. No time to undergo your redemption arc when you’re getting shit done too fast to actually analyze your deep-seated internal conflicts or have your narratively prescribed life changing epiphanies
hang on I convinced myself this is a good idea for an au actually. Because Hakoda would never banish his kids/send them on impossible quests/pull any of stanklord ozai’s other miscellaneous bullshit, so obviously sokka (who loves responsibility, who will literally make himself responsible for any person, place, thing, or idea you put in his immediate vicinity) volunteers himself to go looking for the avatar — the only continuing threat to the water tribes’ chances of winning the war.
And Katara, who would never let her brother do anything that dangerous or that cool without her, goes with him.
So they find the avatar being harbored by the fire nation, they capture him, and they start the journey back to the southern water tribe — but while sokka spends all his time being bossy above deck, Katara spends a lot of her time thinking about the avatar — and who could blame her for wanting to know more about him? No one’s seen an air bender in 100 years, and he’s the avatar.
Katara has always been a little bolder than sokka is comfortable with (see: trespassing on an abandoned, off-limits fire nation ship with a random kid like a day after finding that kid in an iceberg; launching an assault on the northern water tribe’s foremost water bending master because he wouldn’t teach her, even though she was untrained at the time and really shouldn’t have had any chance at surviving, let alone winning; getting herself purposefully arrested by the fire nation to stage a jail break for some earth bending kid she met like 12 hours ago; the entire painted lady debacle).
So it makes sense that instead of just wondering about the avatar, she starts visiting him. And then she starts talking to him. And then he starts talking back. And somewhere in those long weeks it takes to get from the fire nation to the southern water tribe, Katara starts thinking: what if we’ve been wrong all along?
The thing about Katara is that there’s nothing in the world she hates more than injustice, and there’s nothing that could make her stand aside and let it persist when she can do something to stop it — and here is where she starts to realize that maybe she and her people have been primary perpetrators of so much of the world’s injustice for a long, long time, so obviously she does what only the best water bender the southern tribe has seen in generations can do, and breaks the avatar out of the prison that is her brother’s ship. (and when he says “come with me,” of course she says yes; he wants a friend, but he needs a water bending teacher, and maybe helping him is the first step to making things right.)
This is basically my very long-winded way of saying that I had it all wrong in the original post: while having Sokka on your side is basically the necessary condition to winning the war, if there’s anything that might slow him down, it’s definitely his little sister on one of her righteous rampages.
Here is my main point though: in a functional a reverse au, Sokka isn’t the one who takes on Zuko’s role — Katara is.
This of course means that Sokka is Azula — a terrifyingly smart secondary antagonist who is far more intimidating than the primary antagonist, and who spends most of the rest of the series chasing down the avatar and the group of friends he’s somehow managed to accumulate. In this world though, I think Sokka is probably a little more motivated than Azula was (and thus a little scarier) because he’s not just acting on his father’s orders, or for the glory of his people. It’s personal for him, because the avatar stole his baby sister, and Sokka, protective big brother that he is, doesn’t care what he has to do to get her back.
