While at first most rats ran to Mega Burg seeking shelter, as time went on many were curious of the outside world again. Seekers, leading numerous expeditions outside, would begin to establish small outposts in human houses, where finding loot was most promising. Over time, as some rats chose to leave or were exiled new colonies would be formed, smaller than Mega Burg, but using some of the lessons and knowledge gained from their home colony.
One especially popular colony for many makers was known as Scrap Haven. Located beneath a Scrapyard, one could reach it through the sewers and exchange food for all manner of metal bits and pieces. Scrap Haven lacked its own source of food, something Mega Burg had an abundance of, and trade of food for metal flourished.
Even though Scrap Haven was technically part of Mega Burg the elders of the home colony always failed in deciding how to administer it. Protectors, in turn, did not want to waste their resources to station even a single Paw in such a distant place. Because of that smaller colonies like Scrap Haven tend to be largely independent, with their own laws, guards and rulers.
Fighting between colonies did occur, especially if such colonies encroached on each others food supply, but it was never a war to the death.
Very few colonies cut their ties with Mega Burg completely, and those that do usually have a good reason to do so.
The main threat to such colonies and outposts, aside from humans and beasts, are bandits. Opportunists with their own camps who would much prefer to get some free food and other „nice stuff”, rather than look for any of it themselves.
There is yet to be an instance where a colony challenges Mega Burg’s dominance.