Now please note, I haven't seen season 9 yet, so this thought might contradict the Canon, but hear me out.

We've kind of been looking at Ahuizotl as the Aztec Sun totting equivalent of Nightmare Moon, who isn't fully aware of Celestia and Luna's roles with the celestial bodies, and while that might be true, there was a thought that occurred to me.

What if he was partially aware? What if he knew about Nightmare Moon and the threat she posted? What if he knows that Nightmare Moon was defeated but believes that since Celestia spared her (technically Luna)? And what if because of this he wanted to claim the power of the sun in order to defeat Nightmare Moon (killing Luna in the process)?

Now you might be thinking, "but Robipony, Ahuizotl comes across as crazy and maniacal. So he has to being doing this because he's mad." To which I have two responses.

1) What if he is taking his maniacal behavior?
2) What if he became mad as he went along on this quest to defeat the Nightmare?

Again, keep in mind this is just a thought I had. I haven't seen season 9 and while I know he is supposed to show up in it (and possibly throws a monkey wrench into this idea), I thought I would just go ahead and share it with you.

Thank you for listening.

7005038
That definitely seems more like him, I’ll tell you that.

7231626 Admittedly I am using an alternate variation of this with the idea being that when Ahuizotl mentioned that he was going to bring eight centuries of sweltering heat to the wasteland he didn't mean that it was going to get warmer but that he was going to use the rings to keep the eternal night from coming and that the basin would remain safe from Nightmare Moon's influence. Due to his location he was unaware of Nightmare Moon's defeat and as far as he knew ponies like Daring Doo were agents of Nightmare Moon trying to bring the night.

It isn't until around season 9 that Ahuizotl learned the truth.