(Also mind, to be Inclusive).
This is your muse here, and have I got a proposition for YOU. You know how you're working on your dark Untitled Project series about Killers and Thieves and it's pretty grimdark and a fun experiment? Well, hold your horses because I came up with an idea for you in the shower. (I am why you should take less showers, I s'pose.) Begin with casual murder in a cab in a city set in the industrial revolution -- I do hope you're taking notes here -- and build a novel about a class of people who can murder in society with impunity.
Call them Aendar -- you can steal the half-remembered term from a role-playing world you made over a decade ago -- and explore the ramifications of such people to the social orders, ways of stopping them, the nature of their abilities and the extent to which they serve a valid function. If they kill random people without reason too often, they would naturally be murdered, but if they said with the Just vs. the Unjust, do they die sooner? What are the criteria for justice on such a world? And does an industrial revolution require heartless bastards at the core of it running factories without care for people in order to succeed?
And, if so, is murdering such people detrimental to both the nation and social order? How do Aendar deal with this and cope with their (obvious) lack of friends or family? What if they disguise themselves as other people and then it becomes a weird love triangle? What if a state-sanctioned executioner like this goes 'bad' and what would that entail?
Hey, wait? Where are you going? I know it's almost the holiday season and you found out you need to buy one more gift still and you're really busy, but -- hey! HEY! I have more ideas for this!