The first appearance in the story, this character is introduced as Jace Wayland. Later he is also known as Jace Lightwood and Jonathan Chistopher Morgenstern. Jace comes from Wayland family and adopted by Lightwood family since his father is believed to be dead. He lives with Lightwoods and trains to be a Shadowhunters and becomes one of the best fighters among his age. He is a parabatai with Alec Lightwood. He has interest for Clary but in the end of the story it is revealed that they are siblings.

Jace helps Clary in her venture to save her mother. He always protects Clary and help her to find Mortal Cup to save her mother. In the ending of the story, he is told that Valentine is his father. Feeling disappointed, he fights Valentine, assumed to be his father, and tries to protect Clary.