On another note, the Nameless King wrecked my arse for the tenth time.
I have resorted to using bows to fight the Storm Drake. I think the trick here is to lock onto the Nameless King himself to watch what he is doing, then lock onto the Storm Drake once he stops bobbing his head like an oversized fire-breathing ostrich.
Phase 2 still wrecks my arse. I should stay the hell away from his three-hit combo.
Anyway, Aldritch is a nasty piece of work. Also, I think there's some kind of conspiracy here. As I understand it, Irithyll was part of Anor Londo, perhaps one of the surviving districts from the Second Age of Fire (you know, the one with the Chosen Undead from Dark Souls 1). This much I gathered by the fact that Anor Londo was literally next door, and that there is this mansion that houses Silver Knights and some Anor Londo memorabilia, probably the home of a Londo nobility or perhaps a winter retreat for the old gods. Reading the item descriptions of the loot acquired by slaying the Pontiff and Aldritch, I suspected that the Pontiff, and possibly the rest of Irithyll, had a bone to pick with Anor Londo, presumably because of the whole Hollow incident caused by the fading fire. It just so happened that they had Aldritch with them, a priest at the time, who had eaten so many people and had grown powerful enough to challenge the gods, and just so happen to be in the mood for a divine morsel.
So Aldritch ate the gods, the Pontiff modified the existing religion to worship Aldritch, and we got the Cathedral of the Deep.
As for how this ties into the main plot, I think that the Princes, who weren't willing to go and burn in the Kiln again, heard of Aldritch and, seeking to escape being set on fire again, allied with the Deep and did whatever they can to stop themselves from being taken to the Kiln. Probably even started a war, looking at what happened to the High Wall of Lothric. High Priestess Emma was working against the Princes, which was why she was killed.
Anor Londo's not so much next door as upstairs. You know that huge city that you could see by looking off the (numerous) edges in Anor Londo in DS 1, but never got to visit?
That's my interpretation thus far, anyway.
As a side-note, we only know of one god Aldrich ate (the one whose moveset he's co-opted and improved on, the bastard).
The thing that confuses me is that the relative positions of several Lordran/Lothric landmarks have been switched around. Lothric Castle seems to be in the position Anor Londo used to occupy, while Irithyll, hence Anor Londo, is found within a few hundred meters of Izilith, which was at the far end of the map from it in DS1.
It makes more sense if we don't think of this too much as a literal, physical landscape-- an option that gets borne out a little if you get past the Consumed King and find the Untended Graves.
Stuff gets weird.