I thought it would be good to include books that include sex and hopefully lots of it! Well...this is a rape fantasy site...
Here is a nice list I found and was surprised that I had one or two stored on my Kindle (OMG...and had not read them!). The best of both worlds sci-fi, fantasy and the erotic:
Kushiel's Dart - Jacqueline Carey (sadomasochism, futuristic spy vs spy)
High Couch of Silistra - Janet Morris (sexual slavery and war)
Gorean Saga - John Norman (Sexual slavery and bondage)
Touched By Venom (Dragon Temple series) - Janine Cross (sex, drugs)
Lilith's Brood (Xenogenesis series) - Octavia Butler (mind control, incest, tentacles)
The Velderet - Cecilia Tan (BDSM, alien invasion, cybersex, gender-swapping, SM)
Image of the Beast - Phillip Jose Farmer (murderous aliens, kinky and horrific...read at your own risk) (Blown is the sequel)
Bring on the kink...rape...bdsm and whatever else you enjoy!