Essential characters refers to non-player characters, which play a major role in quests. They can be killed either by the player or enemies, when killed a message appears on screen informing the player they have killed an essential character, and directs them to reload a previous save. Characters may become non-essential after certain events occur.
There are some characters, such as friends and members of the Ashlanders, whose deaths will result in angering essential people, and can cause the same effects.
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