Underground

The underground is where all monsters live, since the War. The underground always was a chaotic place, not the best place for children to grow. It is ruled by Azgore after his parents and Toriel's decided to promote him to the King and the patriarch of the Dreemurr family. Since the creation of gangs, the underground became a very unstable place.

Why is the Underground so unstable?
The Underground is extremely unstable because of:
 * The gang threat.
 * Many monsters have a hierarchic mind, trying to control everyone below their level.
 * Azgore the ruler is corrupted, he made unfair changes in the underground just for his wishes.
 * Gaster created so many hybrids and amalgamates. These hybrids became a threat to the population, because of their impurity and their savageness.
 * At least 15% of the population suffered from the Royal Guard's cruel experiments.
 * During the war, the population was ignored by the King. He left them to die without protection and resources.
 * The conflict between the gangs and the Royal Guard is getting worse year by year.
 * Strict laws, if someone writes a journal about how ignorant the King is, the journalist would go to prison for life and even get spanked and abused in public.

Origins
The underground was created by the humans after the War, when monsters lost the battle. After Azgore retreated his remaining troops back to the Castle, 2 magic-professional humans built an unbreakable barrier to seal the monsters, unallowing them to come back to the surface.

When Azgore tried to send his troops back, they came back to him and told him they couldn't keep on going, because something huge, white and opaque was blocking their way: the barrier.

Azgore ordered his scientists to find a way to destroy it, to get revenge on the humans for blocking his path. However, it's been a decade his scientists were still doing research and Alphys finally made a lie, that there must be 7 human souls to destroy it. It is a lie, because she didn't mention that 7 monster souls are required as well. She was afraid that he would suspend her from her job if she told him that.

As time passed, Azgore collected 6 human souls. It is unknown how they successfully escaped from the Guardian's claws, but the only explanation scientists could get is that their souls are filled with unique powers.

Gang threat
The gang threat is a major problem in the underground, and is considered more powerful than the Royal Guard because they are roaming anywhere. Their HQs are usually underground, so it makes it harder for the Royal Guard to track them and exterminate them.

The gang threat includes crime activities, murdering, stealing and persecuting the population. Half of Snowdin City is under control of the EKB gang, while the other half is controlled by RDR. The biggest problem isn't the crime activities, but the gang bangs (Gang fights). Gang bangs result in many deaths, including innocent lives. Gang battles are the most destructive events occurring in the underground, because many gangs are equipped with explosives. Smarter gangs tend to shoot cars, making them explode, causing deadly explosions.

The threat couldn't be stopped since more than 10 years, because of their strength in numbers and their hidden bases.

The gang control doesn't only give bad influences to the population, it also gives the population benefits: they protect the population from Azgore's insane plans and for many years they tried to tell the truth about what was really happening. The bad side, is they are causing the population to rebel against Azgore and creating fights.

Corrupted System
This is another thing that makes the underground dangerous: the Royal Guard. Since Asriel's death and Toriel's escape, Azgore became corrupted, making the whole government corrupted as well. He seems to try hard as possible to hide the Royal Guard's mistakes and hide their cruel side. Cruel law examples are the newspapers laws, if someone publishes a newspaper they would go to prison and if it happens again the publisher will be executed in public. If a gangster tries to steal a Royal Guard car, they would mutilate the gangster to death in public.

The majority of the Underground hate Azgore because the punishments aren't right. Because of the gangster influence, they remained calm and never attempted to attack the Royal Guard. The gangsters kept saying this would be a great mistake, because it will cost their life. Gangsters were the ones who controlled the population's urge to kill Azgore.