Corruption

In Malgrave, corruption is not just a status of political intrigue, but a life altering condition that is brought on by over exposure to fiend blood.

History

It has always been known that due to the unstable nature of Malgrave, the various planes have an altering effect on the people. Although the same, it is not to the extent that one could become a genasi, or be born a tiefling or aasimar, or be touched by the various realms. It is far worse to be corrupted, as it will change mortals into fiends, typically driving them insane in the process. It removes empathy and remorse, causing the afflicted person to revel in cruelty with no known ways to reverse it. Some believe it could be undone with a Wish, but none have ever attempted to do so, usually killing the afflicted person instead to end the suffering they spread. The mental strain on all in the vicinity make forgiveness difficult.
In the earlier times of Malgrave this affliction was not uncommon in warriors, especially during the Reclamation War. Men and women of all races who served as genuine heroes would eventually become another adverasy or villain to face. More than half of all Riftwatchers have eventually succumbed to this affliction as well, becoming dangers to the world they once protected.

Cause and Effect

As fiends are the physical embodiment of evil, their blood is more potent than spending years in the Abyss or the Nine Hells for the people of Malgrave. Any significant amount gotten onto the skin or inside the body leaves traces of darkness behind. It seems to take more to have a lasting effect on those predisposed to good, which is where the term "To bathe in the blood of 1,000 demons is to become that which you destroy" comes from, as most of the original peopke to be affected were protectors and defenders of their people.
These minute traces gradually draw out more and more of the darkness that hides in every person, no matter how virtuous. As it can be a very jarring shift for most people, it is said to make people snap and break as they fight against the changes to their better nature. There are those, however, that seek out this change as a means to power.
Not only does one's mind change, but their body does as well. They become more resilient, regenerating quickly and becoming numb to most pain. The corruption also makes its victim ageless and immune to mortal sickness. Some even gain innate spells and abilities like those of a fiend, changing more and more until they themselves truly are a demon or devil. This is even to the extent that holy water causes immense pain and even death merely sends them to a different realm, not truly dead. Depending who you are, it is a painful, heartbreaking process as they slowly lose themselves to the corruption, or an addictive rush for those who hunger for power. Some are able to retain themselves, even after a complete transformation and are able to become leaders of good or evil.