Harcourt Fitzwilliam

This guy was like, the devil that always whispered in Prince Henry's ear. At the time of writing, wiki pages exist for neither of these characters, so here we go. He is also known ls the Marquess of Blayne.

Season 1
Harcourt is conspicuously low profile in Season 1 except to demand virgins from Lydia Quigley and kill them, and cheat the courts.

Season 2
In season 2, Harcourt finds out about the secret child Lydia Quiqley is hiding for his sister, Isabella. He seeks to find the child, Sophia, not realizing it is his own daughter from that one time he raped his own sister. As a result of the accusations of virgin kidnapping and killings, Harcourt flees London for a bit till things cool down.

Season 3
In season 3 Harcourt pisses off all the women in London. He has Anne Pettifer give birth to his son, whom he bars his sister Isabella from ever seeing. In a bid for power, he encourages Prince Henry to make Kate Bottomley his mistress even though they 'got off on the wrong foot.' He hounds Lydia Quigley to bring him another virgin to be ritually sacrificed, and threats to do this to Kate if Lydia does not comply. He also incites Prince Henry to treat Kate like a high-durability sex doll. He inflicts a fate worse than death on Anne Pettifer when she gives up their child to him for money, but then has one of his henchman mug her and brutally slash her face. After Kate and Lydia plead with Henry to remove Harcourt from power, he appears to do so (casually) the next time Harcourt appears at the cricket grounds (near the manor where he was currently living with Kate, I think it was maybe named once or twice in all of Season 3). While seated alongside Anne Pettifer (her face scarred), Kate Bottomley, and Lady Isabella, Prince Henry verbally relieves Harcourt from his station, commands that he not show his face at court anymore, and warns him that he will have the former governor hanged if any (further) harm comes to any of the women seated around him.

So then when Lucy gets out of debtor's jail and meets Lydia Quigley back at Golden Square, Lydia gets Lucy to drink a roofie or something, in preparation for Harcourt's sexual assault. When Harcourt arrives to rape and kill her, she manages a struggle when he pulls out a dagger and tries to stab her with it. They tumble off the bed, but the Marquess pins her against the wall and starts choking her. Lydia Quigley then takes the dagger and fatally stabs Harcourt in the back. So yeah, no one wanted to write about this lunatic, yw.