Storyline discussion

[Kyra Tierney]

As you may recall, there are always at least two villains. One is Darkfalz, the personification of evil, who emerges from another dimension on millenial basis. The other is a living person from human world, who lets darkness inside his soul either willingly or (as in Rico's case) by staring into Abyss for too long.
PS - La Shiek
PSII - Neifirst (and earthlings)
PSIII - Rulakir
PSIV - Zio
PSO - Rico
PSU - Howser
PS0 - Mother Trinity

So, which character will be the antagonist for PSO2? As of now, we have:
The Mask. He opposes the player in his quest fow weapon shards, is ready to kill him on spot ans is the only outright antagonistic chaacter. However, him wearing a mask, while being an omnious trait also denotes him as someone whom nothing is known about. His motives are still hidden and can tun out to be pretty much everything.
Then we have Gettemhart, a fellow Arks member. He, being an Arks, can be relied upon, as it was shown in first chapter. It should be noted, however, that he is nothing more than an ally and nothing like a friend to player. He doesn't fight for anyting other than just fighting, something he can do no matter which side he is on. He has a firm belief that strength justifies everything and that weak should become prey for strong. Player just happens to be on the same side and it the only reason Gettemhart does not attack him. In fact, his only redeeming quality is him followed by Melfonsina. He can't be that bad if admired by someone, right? For all we know, a good side of him may, which only she sees. may eventually surface.
That said, there is another common plot element to PS series: someone dies. It started with infamous Nei's death and continued up to death of Divine Maiden. (I remember being pleasently surprised by Kai actually surviving his heroic sacrifice in the end of Zero). My speculation for PSO2 is:
Melfonsina will die. When Gettemhart lets darkness overtake him, she will be the first to die to him. Another possibility fo these two that I see is Gettemhart becoming one of those he hunted (being infected by darkers) and Melfonshina bringing him to senses, which may or may not resilt in her deathm after which he will have a change of heart.
On a side note: what is inside Oracle mothership, the one that Arks do not live in? Is there a Mother Brain?

[RocSage]

I think the player is Mask.
Gettemhalt is not n "enemy" and he is not not dangerous because he is an ARKS. There are ARKS that attack other ARKS,

[Zorafim]

Mask, no questions asked. You can tell just by looking at him, that's the roll he fills. Gettemhart's going to be the heartless bastard that has a heroic end, or the heartless bastard who learns about love from the perseverance of the girl who crushes on him. The mask seems to be working directly for the darkers, and even has the black labcoat thing saying that he's bad.

[methaniel]

You should not forget that Matoi has more than probably a link with the darker, so I wouldn't be surprised if she goes to the ennemies side (or something like possessed)
For Gettemhart, he's just a battle-crazed and just like Risa said about him, he's looking for dying in a fight. I don't remember the contents exactly but there was also a cut-scene where Melfonsina explained why Gettemhart became like this...though as I was in a hurry I quite skipped it and didn't checked my log later to read it correctly, something about an incident when younger...
The mask is for now the antagonist, but I don't know, it looks to me as if it's not for an evil purpose that he's looking for the weapons for now (for me, he's doing it to counter the darkers, but that's just my wishful thinking).
If one really had to be taken by the darkness, then maybe Zeno...He's in the position of one of the main NPC, and the way he is, I wouldn't be surprised if he succombed to Darkness because of the pressure he's always giving himself (and for example The Mask could have been his teacher, since I don't remember hearing how he really disappeared and if it's been confirmed, and the revelation could make him snap...but I'm going a bit too far there)