Comments posted to our Dark Souls 3 Wiki
I feel like these dudes were a bit of a red herring in terms of lore and enemies... It's so clearly part of the dark/abyss/deep or whatever, some sort of corruption of humanity from eons before, manifesting as a new symptom of the undead curse. Although, the player characters is no longer an undead, is it, but an unknindled. Which explains how Hollowing now is attainable only after certain actions, compared to the first two games where death made you hollow. Anyways, these creatures only exist in and around Lothric castle/wall, with the only other one outside of Lothiric being Iudex's version (which in reality is still "inside" Lothric). We see some already transformed in the Gardens, and the white drake @ Lothric is afflicted by it too, as we see later on when we attack it's foot. I don't think any item or spell go into any lore for these, and i still felt they led to no satisfying conclusion; for example: Champion gundyr in Untrended Graves having a pus of man as well, or there being a pus of man related item, spell, or npc to interact with there. Would have been awesome if these were covenant related, too, and one could wield a pus of man related item or spell much like that one covenant in Bloodborne that could let the player become one of the Kin. Unless there is some other piece of lore i don't know about, these enemies feel like they were unfinished in implementation, lacking lore...
You mean Iudex Gundyr in the Cemetary of Ash. Champion Gundyr in the Untended Graves is pre-Pus of Man. I agree, though, they really didn't address it much. That thing scared the ever-living***** out of me when I faced it on the High Wall of Lothric for the first time. I thought that was the last time I'd ever see something like that and then a weak-ass undead hollow just up and transforms, killing me.
Judging by the QA Cut Content: - Serpents like Kaathe and Frampt were meant to be the final boss. - Gundyr, infected by Pus of Man, was meant to be Oceiros. This makes Pus of Man have much more sense - it resembles a serpent-like being. All around Lothric there are hints of serpent worship. Oceiros (Gundyr) being the "lord"/researcher that introduced the Pus of Man in Consumed King's Garden (with a bunch of them + poison being there) makes sense. In the end, they've hastily scrapped the whole thing and Pus of Man remains an after-thought.
Cursed flame is fading, and humans begin to assume their true from – of dragons/flying serpents. Even more so, with growing dragon out Gundir, and the Drakes which is spawns same humanity's serpents out them upon killing them for the first time. Humans=Dragons, hinted in DS1, confirmed in DS3.
Most annoying enemy in the game unless you've got Firebombs.