What makes a Protector?

That's a good theory, too. There's one little catch that breaks it for Nero, though. Alis' spirit tells Chaz that "all of our thoughts" are stored in the sword. At the very least, Alis' memory is there as well.

I think Nero was left out because he probably didn't personally fight anyone important. I've always had the impression that Lassic's troops took Nero out before he could get very far into his attempt to stop the corrupt king. Like Komrade said early on, a lot of people would have been killed under Lassic's reign. But Lassic himself wouldn't have fought them all; his flunkies did most of that.

On the topic of Nei, I think Neifirst was heavily influenced by Dark Force, just like Zio. It might have been more subtle with DF acting through Mother Brain to drive Neifirst to do wreck havoc as opposed to Zio's open worship. But I think Neifirst definitely had some DF in her. And like DD mentioned, killing everyone on Mota would have been a big danger to the seal.

Neithird wrote:

I think Nero was left out because he probably didn't personally fight anyone important. I've always had the impression that Lassic's troops took Nero out before he could get very far into his attempt to stop the corrupt king. Like Komrade said early on, a lot of people would have been killed under Lassic's reign. But Lassic himself wouldn't have fought them all; his flunkies did most of that.

On the topic of Nei, I think Neifirst was heavily influenced by Dark Force, just like Zio. It might have been more subtle with DF acting through Mother Brain to drive Neifirst to do wreck havoc as opposed to Zio's open worship. But I think Neifirst definitely had some DF in her. And like DD mentioned, killing everyone on Mota would have been a big danger to the seal.

That's the best theory yet. It incorporates the better points of some of the other ones, and I don't see any holes in it. Zio and Neifirst take care of Alys and Nei's appearances, and Robotcops appear to be the ones that killed Nero; they're all over the place. They're evil, but not a massive evil like Zio and Neifirst. The two of them were major threats to the Motavia seal!

I think the protectors are already chosen before they knew about what is really happen or they are chosen even before they are born.

Just like Elsydeon choose the main protector in PS4, Rune also knew it would be chaz... and he was right. Besides LaRoof said Chaz and his party were "Protectors" witch shows us they already were chosen -> even before they accepted (or at least before Chaz accepted that title/burden).

So, I believe the criteria are not their deaths or what they do. I think it depends on the "Great Light" will.

Spoilered because I think Kaloes might want to not be spoilered on this one.

Nei's spirit is in Elsydeon, I think, because of the New Game + of PSGen2. If you do things exactly right, you can bring Nei back to life after NeiFirst. Let me go find the picture...

Okay, I'm back, and yes, I really did go and find her picture. Wikipedia's page on Phantasy Star: Generation 2 has a picture of Nei on Noah. Not linking it because for some reason, images aren't hidden in spoilers. Odd.

As for Nero's not being in the Elsydeon, Neithird's probably right: Nero was a first level commoner, no magic, no Techs, no items, and just a Short Sword and Leather Armor to gilve Alisa when he dies. How did you think it was gonna end for him? =p