So, in a story, rape and orgasm and perhaps a modicum of realism, can it be done?

Like this, for example. [I am leaving out the name of the rapist in the story.]

A long time seemed to pass before I heard the door open and sensed the presence of my jailor. My release did not come immediately – not until [he] had taken advantage of my widely spread legs and exposed sex, first using his fingers until my loins became uncontrollably wet, then thrusting into me with a vigour I could do nothing to counter. I closed my eyes and let him pump away, the weight of him on top of my own tied and spreadeagled body only drawing everything tighter. I was panting and moaning now under the tape and the mask, partly from the pain of the stretching in my restraints and partly – I admit – from the arousal between my legs. I confess to climaxing, even under such circumstances. I could not help myself and saw no point in fighting it. It did nothing to alter my feelings of loathing towards [him], nor did it lessen my desire for revenge.
Richard Alexander: Vanishing Act

Or like this.

Once again, the cock responded. Despite the boy's shame. Despite his on-going fear. Despite his deepening physical and emotional weakness. AKA knelt and licked the top of the penis. The cock immediately jumped and elongated.
Amazing, just amazing! AKA thought, still surprised that a kid could get hard and cum – not once but any number of times – in such a situation. [...]
AKA opened his mouth and went down on the cock. The kid's thighs flexed, his legs straightened out from the bed. AKA moved his hands down the legs, back up them to the boy's waist, around to his back as he engorged the seven long, lean satisfying inches to the hilt. Donovan groaned in pleasure. It was not a pleasure he wanted, of course. There was no conversion to a new and exciting lifestyle in process here. AKA was no fool. The boy was being raped and he knew it, would never forgive it, and, if given the chance, would make sure AKA paid for it, but he responded to the pure physical pleasure of what was being done to him whether he wanted to or not.
Jason: The Chosen One

Quote Originally Posted by carrie
As far as I'm concerned if it's turning you on, you want it!
In a consensual situation, yes.

With adequate stimuli, more refined than the giraffe/Louisville Slugger combination, it can at times be plausible if characters get turned on without having consented to any of the sexual activities they get subjected to. Arousal is arousal, not consent. The fallacy ‘If it's turning you on, you want it’ is used ad nauseam by writers who invent a nonconsensual situation and at the same time feel compelled to deny it.

The epitome of this absurdity, if used in writing about a rape situation, is the phrase ‘His body betrayed him’ or ‘Her body betrayed her’.