
This HaBO request comes from Caroline, who is looking for this historical romance series:
So I’ve been searching for this novel/series and haven’t been able to turn anything up on my own. Here’s everything (and I mean everything!) I remember about the book(s):
It’s a historical romance trilogy about three sisters. I think one of them might be named Kate, and there’s one whose nickname is something like Syn or Cyn. S/Cyn is the wild one of the three, and her book’s hero is named Harry or something that starts with an H—but his nickname is “Danger,” so they’re “sin and danger” (get it?). I remember almost nothing about the plot except that at the end S/Cyn has left the city to live alone in a house on a hill, and Harry manages to find out where she’s gone and goes to dramatically confess his love for her. After he does so, she reveals that she’s pregnant. I read it back in the 2000s, and unfortunately I can’t remember anything about the other two books in the trilogy.
I know it’s not much but I’m dying to figure out what these books are!
The Cyn/Syn nickname feels very familiar.

This sounds like some of the Cynster books by Stephanie Laurens. There’s the Cynster Sisters trilogy about three sisters – none of their names match the HABO afaicr, but there is a Harry in another book earlier in the series whose eventual brother in law gets his own novel.
This sounds a little like Loretta Chase’s Dressmaker’s series about three sisters, the middle one is about Sophie and Harry in Scandal Wears Satin.
I think this is Bertrice Small’s three-in-one volume Vixens. The third story has a heroine Cyn who leaves at the end and her hero (Harry or so) has to go find her on a hill, and she doesn’t reveal her pregnancy until after he’s proposed. https://www.fantasticfiction.com/s/bertrice-small/vixens.htm
“The Cyn/Syn nickname feels very familiar.”
It does! I think I’ve seen it in a number of books, including as the hero’s name in Jo Beverley’s My Lady Notorious (which definitely isn’t the HABO, unfortunately).
I’m sure it’s the Bertrice Small book. Cynara’s story is called “Cyn and Wickedness”.
Suzanne Enoch”s Meet Me at Midnight has a heroine and hero named Vixen and Sin. It’s part of the “With This Ring” trilogy and there’s a big pregnancy reveal.
“Meet Me at Midnight” is a very good book, so I recommend reading it regardless!
The story sort of reminds me of Lisa Kleypas “Wallflower Christmas” or Wallflower Quartet Christmas (whichever?) Anyway, maybe?