The Comment Zone is a channel through which beings from across the zones can influence the actions of individuals. The main target of their influence so far has been Ms. Green, but it has been stated that anyone can be influenced by commenters.
The commenters have several powers at their disposal. The first is commenting and suggesting unique actions to move the story along. Secondly, the commenters are capable of creating Fanon, which is an alternate, subjective twist on reality. The third way commenters can influence the story is through "dudl.me," which allows commenters to draw on the page through a third party.
"The commenters themselves are something kind of horrifying, but we might never find out what. They’re not malevolent, but they are a canon influence that mostly thinks all this is just a silly game, so they’re not harmless either, and they could be anything at all. Brain parasites, a sapient virus, omniscient bumblebees from one of the omniscient bumblebee zones, who knows."
"Whatever they are, they are probably a normal force that also influences us regular humans in our own zone. Since the protagonist (Ms. Green) is now in a different zone able to interact with things we can’t perceive, she’s at least dimly aware of them. (Bogleech)"
"A comment swarm won't be an automatic influence; otherwise we'd have too much spam! What really matters if when comments collectively give me a new idea, or change what I was thinking would happen next!"
The commenters congregate in large hives for different purposes. Despite potentially being from different zones, these creatures are able to navigate through to construct these hive mind projects.