Nate Gray

Nathaniel "Nate" Gray was the son of Harriet Moore and her late fiancé, the adoptive son of Elizabeth (Adele Starkweather) and Richard Gray, the adoptive brother of Tessa Gray and an antagonist in The Infernal Devices (prequel series to The Mortal Instruments) books Clockwork Angel and Clockwork Prince.

History
Nate was born in 1859 in London to Harriet Moore. His father had died before he could marry Harriet, but Harriet's sister (really adoptive sister and a Shadowhunter named Adele Starkweather) Elizabeth and her husband Richard raised him to save Harriet from the shame of having a child out of wedlock. In 1862 when he was around three years old, Nate, Elizabeth, Richard and Harriet (whom Nate believed to be his aunt) left London for New York where soon after Elizabeth gave birth to her daughter Tessa (whom she had with a demon disguised as Richard which was sent by Axel Mortmain to make her pregnant with Tessa).

Three years later when Nate was six and Tessa was three, Elizabeth and Richard died in a carriage crash and so the two were raised by Harriet. Feeling guilty for never telling Nate that she was his biological mother, Harriet spoiled him and let him get away from everything. But as Nate got older, he started drinking and gambling and ended up losing money which Harriet worked hard to get back.

Sometime later, Nate got into gambling depts and decided to look for jewelry in Elizabeth's jewelry box to pawn, but instead found pages from her diary. Reading these pages, Nate discovered that Harriet was his mother and this caused him to hate her for this and also learned about the Gray's connection with Axel Mortmain and his adoptive parents' introduction to the Pandemonium Club before their departure to America. Nate tried to use information regarding Mortmain's occult practices to blackmail him in hope of getting money or employment from him. But instead, Mortmain arranged to have Nate brought to London as he was unsure if he was the child Elizabeth conceived with the demon. After discovering Tessa's existance, Mortmain decided to use Nate's anger and connection towards her to his advantage (as Nate had come to look down on Tessa after learning of her demon heritage) and offered Nate a job with his company which Nate agreed and was introduced to the Pandemonium Club and became entranced by the supernatural dealings there and became loyal to Mortmain and hoped to serve as his right hand man when Mortmain would rule The British Empire.