system
Given the following post, respond as if you're commenting on Reddit:
human
[ATLA] Since Sozin and Roku were born on the same day, what would have happened if Sozin had been the Avatar instead?

Would he still start the War? Would it even start sooner? Would he even be allowed to leave for the customary 12-year Avatar training?
gpt
The influence of the Avatar's reincarnated spirit, plus Raava being the spirit of light, means that all Avatars are compelled to be helpful and kind in pursuit of balance. (note that being kind doesn't always mean being nice to everyone. Kyoshi was a major example of that) Their world-travels and years of training means that they connect with people all around the world, and strip away any prejudices they might have had in their young lives. Avatar Sozin would have ended up almost exactly like Roku, though maybe a little more heavy-handed in his approach to things, much like Kyoshi had been. 

If Sozin was still born the heir of the Fire Nation on top of being Avatar, he would have relinquished his throne in favor of a sibling or close relative. Because being the Avatar is far more important than the leader of a single nation. And the sages/white lotus/other organizations would have impressed upon him that fact. We have no idea what Sozin's family was like, so they still might have had the same processes that Firelord Sozin had, and perhaps still started the war. It wasn't until after Sozin took the throne that he instituted many reforms that transformed the Fire Nation into its most well-known incarnation. Before that, many people in his nation were highly spiritual and would not have balked against the advice of the sages.