by skarekrow13 Tue Jun 25, 2013 1:27 pm
Everything's actually for gameplay purposes. The lore is just for us to have fun with since there's very few things that can be proven.
Anyway, here's the reasoning I have for the need for a host/guide.
Four Kings: Due to their threat to the outside world they needed to be sealed. This implies that they would spread without the seal. Again, water is often used as a means to seal evil in mythology/fantasy. We remove the seal either by killing the guard for the key or proving that we're able to follow in the footsteps of the last person to "traverse" the Abyss safely. This corroborates the need for a seal lest something bad happen, aka the Abyss or threat spreading.
Once we kill the Four Kings, there are several interesting things to note. We no longer need the ring to "traverse." Yet prisms still fall through the "floor." Also, while seemingly infinite, you can use the fire as a reference to show that you can only access a set area. This could be just gameplay but it could reinforce the idea that only a "pocket" of Abyss had encroached so far. Why is the ring no longer necessary though? It's my take that the Abyss is now unguided by the Kings. Without a hostile will, the Abyss is no longer hostile. Is there more evidence of this? Why yes. After killing the Four Kings, Ingward's job is suddenly meaningless. He will depart to Firelink and is now unconcerned with the Abyss. A person who seemingly has dedicated an eternal life to ensuring the integrity of the Seal abandons it. It's safe to say that without the Four Kings; there's no threat. The Abyss is still there. But there's no threat.
Manus: Similar idea, he obviously is not sealed with water and it looks like that part of the Abyss has spread further, corroding a lot of terrain and destroying Oolacile from below. The Abyss shows indiscriminate destruction. Or does it? When you fight Manus, isn't it strange that there's a perfect arena for him to hang out in? Almost like it's providing some ground for him since he's not a wraith. And when you kill him....once again the threat stops. Elizabeth hints that it's too late for Oolacile (like we didn't know that already) but that the threat of further encroachment is gone. Fast forward to Darkroot instead of Royal Wood and we see that the Abyss has indeed receded.
In both instances the Abyss is harmless by itself, neither harming nor spreading.