Somewhat detailed
Two people who are fundamentally very different are actually the same person split in half. They hate each other and are fighting a war against each other as very strong soldiers. Different soldiers talk about them on the battlefield and the two people hear this, although at different times. They eventually agree to meet up and realize that their personalities although opposing, are basically "Im the good side" and "Im the bad side". They talk it through and realize that all the hardships they have faced were basically the same event at the exact same time. While they are together and talking the war ends on a ceasefire and they realize that while they are together good things happen, but while they are appart bad things will happen. They end up goung on this whole adventure through mithical things, going through ancient relics of the past and yada yada. In one adventure they meet a corrupted god and it just so happens that they have a purification object on them, they defeat the corrupted god(corrupted gods are much weaker than regular gods, and these two people are very and i mean very strong) purify it and talk to it. The purified god talks to them and is like "Oh I seem to recognize you." and the two are like "WTF.". Also it turns out that even if the purified god is now purified it was still on the verge of death and is now almost dead. The purrified god, with the time it has left, tells them about a god who had dual personalities. These personalities were very much like how those two people acted and these two people gave off the vibe from that god. The god then Says "Oh but it cant be them, that god died a long time ago." The purrified god dies and the two are left wondering about that strange encounter. They continue their adventures and meet another few corrupted gods who all say the same things, and now the two people are thinking 'WTF like why are all these gods saying that we act and feel very similar to that one god with dual personalities.' Anywho they finally meet a god who can tell them what is going on, and that god says that the dual personalities god was split in half because together with their dual personalities they were so chaotic. But just before they were split, the gods knew something was off and looked down at the earth and realized. The god with dual personalities was actually taking in most of the chaotic energy, and transforming it into purified power that kept the god realm standing (that god was one of the founder gods). So the gods ended up trying to put back together the god, but couldnt because they didnt know where the fragments ended up. The two people are like no way am i going to become one with that guy, but they also thought that staying with that guy wouldnt be so bad. So thats what they decided, they would link their lives together and never leave each other side(you can interpret that in any way you want, or you can go off the rails).