I've always enjoyed forced impregnation fantasies.
One of my all time favorites is the forced impregnation of a hot lesbian like Portia De Rossi...
To me, raping and impregnating a hot lesbian is a triple pay off
1] We already said she's hot. Having that form hot body to use as my toy is a pleasure it's self. I'd hang her up by her wrist first, just to admire my catch while I slowly cut her clothes away to reveal the smooth female form that I now own. I'd hose her down and wash her clean with a big soft sponge.
Then it's flat on her back in my bed. Her arms cuffed out to the bed posts, and her legs spread wide open, and tied overhead just high enough to lift her ass slightly off the bed.
I can mount her, still have her tits for toys, and best of all, watch the expressions of her face as I rape and impregnate her.
2] She's a lesbian, she doesn't want it, so you are almost guaranteed one hell of a fight as she tries to avoid your dick. The more she doesn't want it, the more I enjoy putting it in her squirming little pussy.
3] Getting to cum inside her (and you know she'll fight that most of all). I'd want to tell her what I have in mind, so she knows what I'm planning , and is helpless to stop me. I'd love watching her face as she feels my load filling her cunt. Then keep her like a caged pet, while she helplessly watches her belly swell as my seed grows inside her.
Damn! Too hot!