The Nexus is a massive structure that lies attached to Stem City's walls. It's the beating heart of Stem City's economy and influence. Without it, society would collapse.
The main building has several floors, including: a floor for emergency medical services and storage of Stem City's Lawmen transport vehicles, four built for systematically storing all of Stem City's excess goods it obtains from trading, two dedicated to storing and fixing Stemrail trains; one winding roundabout floor for sending and receiving Stemrail trains; and one for the administrative/computing office. A hidden basement contains the Nexus' Marks gold vault.
The majority of the Nexus is automated. Beyond the single manager, a group of Lawmen Type-3 control incoming and outgoing requests, scheduling them, requesting engineers for maintenance work, and performing simple PR. Ann Peelo, the current Nexus manager, is practically only there to manage the engineers and for when big Stem City investors need to talk.
The vault has a secret Stemrail that connects directly to The Complex. Whenever the Nexus runs into the rare event it's out of gold, it pulls from The Complex's stash.
XX210 marked the beginning of the Era of External Expansion for the native Stem Rams.
The citizens watched as glowing green portals formed far in the distance. It was not long before a sentient alien race contacted them by sending a group of diplomats. Thankfully for the tribal Stem Rams, this civilization was made of powerful, benevolent people of religion who desired to see their land reach its true potential.
As more outer galactic races appeared in Stem City, it was this race of powerful monks who protected them from warlords, empires, and companies that wished to exploit Stem Island's unique position. The Council of 12 and this race of religious aliens worked together to usher in a new future for Stem City: The Nexus. It would allow the greedy to get what they want from the wormholes while supporting Stem City's own needs. If one group plotted to take over Stem Island, then the other companies would defend them to earn favor with the Nexus.
Over the next century, the project was carefully planned out and constructed with help from several allied off-worlder nations. Hundreds of aliens migrated to Stem City to both settle down and help with the Nexus. The day it finished completion was officially deemed as "Connectionay", a jolly celebration of the extradimensional peace that the Stems and off-worlders had found together.
As Stem City's relationship to off-worlders has fluctuated heavily throughout history, one thing has remained the same: as long as the Nexus stays operating, gaining and maintaining Stem City's favor will remain a primary task for many powerful off-worlder groups.
Ann Peelo became the current Stem City Nexus manager in XX798.