The Rats of NIMH

The first recipients of Dr. Schultz's intelligence formula while at NIMH, the Rats have faced incredible odds to survive their escape from NIMH. They first settled into a colony underneath a rosebush on the Fitzgibbon's farm, living decadently off the work of the farmer and stealing food, supplies and electricity from him. Some began to question the morals of their activity, and some began to fear their activities would lead to their discovery, while others felt they deserved some recompense for their suffering at the hands of the humans. After their close brush with death or recapture at the hands of NIMH, they left the farm to follow Nicodemus's plan to move to a new home Thorn Valley, a wildlife sanctuary where they could live with little fear of human discovery, and without stealing. Some of the naïve among them thought that Thorn Valley would bring an end to their troubles, but the Valley is full of its own challenges, and not everyone has adapted to their new life to the same degree. With their superior intelligence and strength, however, they have so far managed to survive as a communal, agrarian society.

The Brisby Family

The head of this family, one Mrs. Elizabeth Brisby, has been instrumental in saving the Rats of NIMH from certain destruction. Twice. It was her that told the Rats that NIMH was coming to find them on the Fitzgibbons' farm. When Dr. Schultz rediscovered the Rats' colony at Thorn Valley, she saved them again, using the power of the Stone to cause him to forget that their colony in the Valley even existed. As such, she is somewhat of a revered figure amongst the Rats, and her family has been welcomed by the majority of the Rats to live among them--though there are still those who resent her for her part in the downfall of Jenner and the change in their way of life, despite this.

The New Mice

Part of a second group of experiments performed by NIMH, they later escaped and joined the Rats of NIMH at Thorn Valley. While they have done their best to fit in, some of the Rats feel that they don't particularly owe this group any favors; things are tight enough as it is already.

The Rats' Experiments

A small group of feral rodents that had become friendly to the Rats volunteered to be part of an experiment to try to re-create the NIMH formula. While they developed a procedure that was met with some success, it was ultimately discontinued when they found that there was too high a probability for the mutation to cause impairment or even death. However, the survivors of this experiment continue to live with the Rats, who feel indebted to them for their participation in such a life-altering experiment. Some might even say that they are allowed to stay out of a guilty conscience.

Later, however, a female rat and outsider to the colony known as Rapta gained access to the materials on the experiment, and used it for her own presumably maleficent ends. Not much is known about the results of her experimentation, but the remains of several feral rodents seemed to indicate that whatever modifications she made to the procedure were even more injurious. Only a couple of her experiments survived to escape her, also joining the Rats later.

The Ferals of the Valley

Naturally, the area the Rats moved to was not wholly unpopulated; many animals, both predator and prey, lived and died in Thorn Valley for eons while Nature kept everything in a sustaining balance. When the Rats came with their large numbers, superior strength, and strange, human-like ways, many of the animals were curious of them at best and fearful or mistrustful of them at worst. While, by living underground, they could avoid displacing or disturbing most animals, the same could not be said completely of their farming efforts. In order to make the Valley a safer place for them to live, they have also attempted to drive the predators away from their colony and farms. This has caused an overabundance of prey species, and with food becoming scarcer in the valley, they have begun to turn to the abundance of the Rats' farm to subsist. The overabundance of prey has also begun to attract back the predators, in spite of the Rats best efforts to keep them at bay.

While the Rats are indifferent to most feral creatures--as long as they leave them alone--, they regard some of them as allies, helping them to meet their needs in various ways. Some fear that these animals may be only mercenary in nature, but others have developed true friendships with them despite their differences.

The NIMH Mouse Colony

Once thought to be lost, the few mice that were blown away by the ventilation system during their escape from NIMH with the Rats were able to complete their escape. Unable to find the Rats, they went their own way, using their smaller size and numbers to elude detection even while keeping close to human habitations. After stumbling upon a library and feasting upon the knowledge there, they settled down in a junkyard on the outskirts of a human city, building their own colony underground--a marvel of technical skill and accomplishment as they used the plentiful raw materials around them--or stole them--to supply themselves with the highest standard of living. Not just electricity and running water, but nearly every technology that humankind has to offer. While some of them recognize a certain need for independence from humans, they have become distracted not only by their technology but by threats from the highly vicious rats living in sewer and storm drains near and connecting to their colony, with much of their resources devoted to protecting themselves from the encroachers.