What would Xerath do in oppressive, immense Void Invasion?

I asked this question to Jaredan, thanks a lot to him he answered. Actually, even while I'm annoymous he answers a lot of my questions.

But there is something that I dont understand. This answer is brutal. He literallys say he would fight against both sides. Voidborns and Runeterrans.

The things are, Void is the biggest threat for Runeterra. If Runeterra falls, you probably have no possible way to clear them from Runeterra again. Even if you could, there wouldn't be something such as life anymore (except a few Voidborns ofc). There wouldn't be something to rule, there wouldn't be something to show your power that highly feeds your ego, which is a perfect pleasure for an arrogant entity like Xerath. Which is what Xerath wants a lot. His literal purpose is getting more and more power + absolute rule. (Ruler of Runeterra)

Why do I feel like Xerath would make an ally with Runeterrans, at least with such as Noxus, Demacia, Zaun or whatever for a short time? Until they clean the Voidborns? But why would he do that? Most probably because of the things that I said above. Of course totally not with Azir and Nasus, but Xerath is not an entity who could crush anyone he sees. He is not a mindless creature like Rek'Sai. He can talk with you, he can try to use you for his benefits. Examples are followers of Xerath that killed by Nasus.

I just wanna see Xerath in good side for even a short time, even when it is for his benefits. It would be cool and make him totally a grey character, rather than the biggest threat after Void. Really, he is even more dangerous than Shadow Isles in douchebag mode.

So, what do you think? What would he do in your eyes? What would he become? A total asshole, or a powerful ally? Or goes crazy and figures he can dry out the void energy even while he knows nothing good will come from doing this?