Pretty sure Elf Noir would be R.
A lot of fantasy violence, which I think would be a lot more graphic and upsetting to see it on a screen rather than read about it. I toned down some of the graphic descriptions in editing. Sensitive and troubling topics. Light swearing. Adult situations, though hardly any direct sexual content at all. Complex moral questions.
My other novel which is not (yet) published here, I think would best be characterized as PG-13, but others might think R. It's a fantasy novel written with classical antiquity moral and religious practices and mores, and an important subplot involves an idealized variation of Greek temple prostitution in which citizens bid for the right of a night with virgin novices. I'm so immersed in writing within those historical societal practices that the characters don't think much about it or question it as it is part of their religious culture, but to modern readers it may just be so different and contrary to our values as to be morally upsetting and unduly detracting from the work as a whole.