Isabelle says the Queen of the Seelie Court has requested an audience with is

My name is Ashallyn'darkmyr Tallyn, third son of the Unseelie Court...Let it be known--from this day forth, I vow to protect Meghan Chase, daughter of the Summer King, with my sword, my honor, and my life. Her desires are mine. Her wishes are mine. Should even the world stand against her, my blade will be at her side. And should it fail to protect her, let my own existence be forfeit. This I swear, on my honor, my True Name, and my life. From this day on..." His voice went even softer, but I still heard it as though he whispered it into my ear. "I am yours.