Yil was a Striker guard in the Rose Palace who guarded Shai while she was crafting Ashravan's Essence Mark.
Shai forged a letter from the Bloodsealer to trick Yil. She made Yil believe that the Bloodsealer was collecting nails, hair, and personal items belonging to him and the other guards in order to take control of their bodies and kidnap someone. Yil and Hurli went and roughed the Bloodsealer up a bit, which resulted in him drinking too much and being too late to renew the stamp imprisoning Shai.
Shai believed that Yil and her other guards would be reassigned to a backwater guard post after she finished her work, possibly guarding passes to the Teo Peninsula.