HaBO: Two Harlequins, One Searching Reader

Jessica writes in looking for two books she lost:

I'm looking for two books, both Harlequins. A bit of backstory: I grew up in
a duplex my parents owned, and they rented out an apartment behind our
house. We had the tenants from hell in 1995 (to give you an idea, they
played dance music at all hours of the night and tried to sell the
appliances to pay the back rent), and when my mom was finally able to evict
them they left behind stacks and stacks of 1980s Harlequin romances. They
were everywhere: Small piles in every corner of the apartment, behind the
toilet, in the oven, on every shelf in the kitchen cupboards. We're still
puzzled over why they left them; while my mom isn't big on romance, she
doesn't hate Fabio or anything.

In all, there were 70 Harlequins left behind in the apartment. Being 12
years old, an avid reader, and still a little traumatized after reading
Flowers in the Attic when the girls passed it around in class, I helped
myself to a couple of them on the sly before we donated the rest to a thrift
store and kept them hidden in my room. And to save my life, I cannot
remember the titles or authors of the very first Harlequins I ever read.

 

I think it was published in the mid to late '80s. I don't remember the
series it belonged to, but the heroine was named Annabelle, around age 26,
and she was described as brunette with dark eyes. She was spending time in a
castle or mansion, which may have been left to her by a distant relative,
and the castle or mansion was being maintained by the hero. I don't remember
his name, but he was tall, dark, and handsome (of course), and in keeping
with the style of the times, a little distant and uncommunicative. Because
of Annabelle's education and past travels, he assumes she's a woman of the
world, and being the '80s, he finds out she isn't when he least expects it
(*ahem*). I don't remember his name, either. The cover featured a
dark-haired woman in yellow or light green standing in front of the castle
or mansion.

The second book was a Harlequin Historical, also published in the '80s, and
I remember a little more of it: It was set in France around the time of the
revolution, and featured a noblewoman married to a man who couldn't bear
children. She goes to a masquerade ball and introduces herself to the hero
as “Mystere,” figures he'll do to knock her up, and ends up pregnant. The
husband looks away when she produces a baby boy, and shortly after dies. Six
years later, the hero and heroine meet up again, and the hero is quite
disturbed to find out he was used as a sperm donor by a married woman.

I've been Googling these for longer than I care to admit, and not knowing
the titles is driving me nuts.

That second one sounds like the historical romance version of Heart's All I Wanna to Do is Make Love To You, which is a song that will take root and live in your brain if you're not careful – so I won't link to the video. Anyone remember either of these two books?