Jonathan Morgenstern / Sebastian
Jonathan Morgenstern is the son of Valentine and Jocelyn. He is also the brother of Clary.
He is described as being very tall, with silver hair and dark eyes like his father.
Jonathan doesn’t appear in the books until City of Glass, where he poses as Sebastian Verlac.
He later is discovered to be in fact, Jonathan, however most people do not refer to him in that way, and keep his name as Sebastian. He was experimented on by Valentine whilst in the womb with Lilith’s blood, and he repulsed his wn mother, Jocelyn, who knew that something was wrong with him.
Although Jonathan refuses to awknoledge that Jocelyn is his mother, he deems Lilith as his mother as her blood runs through his veins and she aided Valentine with his childhood.