After the destruction of The Wall, The Night Court, in an attempt to protect the human population from the High Fae invaders, decides to try to appeal to Graysen and his father Nolan, who, as wealthy humans lords, have extensive lands and wealth and a fortified castle that remains largely unoccupied. They attempt to deceive Graysen and Nolan, pretending that Elain, Graysen's fianceé, is still human and not High Fae like her sisters, believing that she can sway her lover and his family. However, Jurian has already revealed the truth to Graysen and Nolan. Despite this attempted deception, ultimately, Nolan is convinced, or rather threatened by Jurian, to admit human refugees. Graysen, however, is furious with Elain for not only concealing her true form but for failing to reveal that she has a High Fae mate, Lucien. He subsequently ends their engagement and demands she return his ring. Elain is reduced to tears, but does not comply. Nesta then smacks him upside the head, claiming that he "never deserved her" anyway.
Later on, Elain is lured from the safety of the Illyrian war camp by The Cauldron, posing as a remorseful Graysen. The Cauldron then transports her to the Hybern war camp, but she is rescued by her sister Feyre before any lasting damage can be done.
During the final battle against Hybern in the Mortal Lands, Graysen and his father, led by Jurian, are part of the human army that, alongside an army from the Autumn Court and a small force from the Spring Court, join the fray, reinforcing the battered Night, Day, Dawn, Winter and Summer courts. In the aftermath of the battle, Graysen ignores Elain and departs alongside his father without saying a word to her.
Nesta described Graysen as "kind enough" which must be true considering her protectiveness over Elain. He was said to be as smitten with Elain as she was with him, however, his hatred for faeries is so great that it overcame the love he felt for her. Despite what he'd previously felt, his attitude caused him to lash out at her.
Graysen is a tall, handsome young man with brown hair and blue eyes. He has a solid build.
- Graysen's father, Lord Nolan, had built a wall around their house so tall that not even the trees could reach it. Nesta thinks that it looks like a prison.
- A Court of Mist and Fury (Mentioned only)
- Wings and Embers (Indirectly mentioned)
- A Court of Wings and Ruin (First appearance)
- A Court of Frost and Starlight (Mentioned only)
- A Court of Silver Flames (Mentioned only)
- A Court of Wings and Ruin: Chapter 54