The grey zone is a matter zone also known as the "real" world. Most residents are incapable of travelling through zones under their own power and cannot exist outside of zones with the matter precept engaged. Their disability is mostly caused by the damage done to their exospine during infancy caused by furlers. Grey zoners have the unique trait of experiencing what they call "time". Usually death is permanent for then, unexisting in any form or place. Their conceptual core is usually located in their only existing perceptoid (physical body), meaning that when their perceptoid expires their core is destroyed as well, permanently killing them. They can keep existing only through branchination, something they don't do under normal circumstances. Other zoners branchinate regularly and don't die permanently. Unless all their branches are shed. According to Dr Phage, the most dangerous zone for grey zoners of any category is ironically their own native zone, where they have a 100% rate of eventual mortality due to the unprotected nature of their conceptual cores and steady background reverberation. On the other hand, for a revaporazored or ungibleted grey zoner the safest zones are the violet through chartreuse. The grey zone and its relation to other zones can be compared to a slice of Oumblant, where the center of the hwom is occupied by a colorless and flavorless paste devoid of meaning, in contrast to the rest of the colorful hwom segments that represent the other zones. Some may consider the grey no true zone but an absence of zone, a vast emptiness of disconnected matter inhabited by degenerate quasi-perceptive sub-entities who eventually permanently die. In other words, unlike other zones the grey is mostly empty space with clots of dirt (planets) and other celestial formations situated at large distances. If attempting a perceptual shift between the green and red zones, the grey zone obstructs the path. Some consider it's beneficial and fine if the grey was unexistified, allowing the perceptual conduits to be open for everyone. Phage disagrees, stating that "all zones are important. Probably".
Grey zoners are also highly susceptible to core-altering like that used by Burgrr. But they can also have the advantage of noticing changes that other zoners believe where always like that, like when some element is introduced or removed and everybody except the grey have their memories altered thinking it was always like that.
The "Suckler" may be responsible for the phenomenon of "dark energy" in the Grey Zone.
One theory I've always subscribed to is that there are other, "higher" zones that resemble the grey-zone. The (human) inhabitants of these zones are more awake to the universe they're living in than grey-zoners, but are still unable to comprehend the full perception range. Back when we used to do more role-playing in the comments, I RP'd as a fictional version of myself from the "blue zone", and I think there's one that's semi-canon called the "para-violet" or something like that... -- George Parkins