The Zimtives layer looks like a warzone. It appears to be the suburbs featured in the invader zim show, but it's very clear that there have been numerous battles fought here. The buildings have been repaired enough to keep them livable, but it seems the residents of the layer don't care about making the buildings look pretty, what with how common fighting is here.
The zimtives are all introjects from the show Invader Zim with varying levels of adherence to canon. The layer began a while back with just Zim, Dib, Gaz, and Gir, but it has since expanded vastly with various combinations of each four as well as various side characters from their show. The zimtives exist to release dangerous impulses for the system, which they express by spending a great deal of their time at war with each other. They've been doing this so long, their wars work like a well-oiled machine, with the maximum amount of chaotic expression and the minimum amount of cleanup required afterwards. Between battles, which they refer to as "the narrative", they're all quite civil with each other, viewing the battles they fight more as a game or a "day job" than a life or death matter.
A very conniving little alien, Zim is often found creating new schemes to further the plans of the Irken Empire. Outside the narrative of the layer, he enjoys baking new recipes and making sure the rest of his layer is doing well after the latest narrative escapades. While it often disagrees with Dib, it tries its level best to stay civil with him during downtime.
Dib is a scientist, first and foremost, and he spends his time trying to use his vast scientific knowledge to protect the earth from Zim. Outside the narrative of the layer, he still enjoys doing science, but this time for both sides. They try their best to see everyone's side in an argument, though it gets difficult sometimes when Zim is the other party in the argument.
Zibdoc appears to be a combination of Zim and Dib, dressed like Doctor Membrane. They're mostly referred to as Doc, and act as a mediator for the layer. Outside of the narrative, Zibdoc makes sure that no arguments that start up go too far, and within the narrative Zibdoc switches sides often, seemingly choosing to go with whoever can offer doc the most interesting bit of science - when in truth they switch sides based on how they can best keep the conflict fair and interesting.
Gaz previously acted as the main mediator before Zibdoc showed up, and seems quite relieved to not have to do that level of mediation anymore. Gaz spends most of her time playing games between the narrative, and during the battles it makes sure the damage doesn't get out of hand. Occasionally, Gaz steps in as her own side of the battles, expanding the fight or shutting it down as needed.
Gir, and his army of duplicates, act as a wild card in the battles. It usually comes in either helping Zim or as its own faction, often changing the whole tide of the fight in an instant. Outside of the battles, the girbots work hard to maintain the layer, and the original Gir himself always dedicates some time to checking on the other major players in the fights to make sure everyone's feeling alright after the previous battle.