Grisha are humans who practice the Small Science. Grisha are divided into three orders: Corporalki, Etherealki and Materialki with each order being further divided into specialized types. At times, Grisha are born with rare abilities to summon light, as seen with Alina Starkov, or darkness, as seen with the Darkling, who both fall under the category of Etherealki.
Often principles such as 'like calls to like' are used to explain Grisha power. Grisha see their powers as extensions of the natural world. As an example, Fabrikators do not create metal: rather, they have the ability to alter it.
Ravka relies on Grisha for safety against its enemies. The Second Army is made up purely of Grisha and was led by the Darkling. They are often referred to as 'The Second Army', and though they do the majority of the fighting and inflict the most death upon the enemy, they are not considered as a normal human and are often regarded with suspicion and distrust by the people they fight to protect and the human soldiers who serve in the 'First Army'.
There is a tentative alliance between the First and Second Armies, both having contempt for each other. This is pronounced by the fact that many Ravkans see Grisha as corrupt sorcerers. However, they all lie under the weak leadership of the King.