Rape is a crime in which one agent external to another forces the latter to engage in sexual activity. By "forces" the law means the activity was initiated and consummated against the latter agent's will. The law also assigns responsibility for that consummation to the former agent. The former agent is guilty of rape by depriving the latter agent of his or her freedom to resist the influence of the external agent.
Determinism is a doctrine in which one or many agents external to an agent force the latter to perform any and all of its actions. By "forces" determinism means the actions were initiated, sustained, and completed wholly on account of conditions external to the latter agent. The external agent (or the set of determining conditions) is the explanation for the latter agent's actions, and this because the latter had no freedom to resist the deterministic influence of the former.
How does rape differ from being a mere deterministic event? Why is a rapist guilty of assaulting a victim but a falling tree is not guilty of assaulting its victim? Compatibilism seeks to integrate "having a will" and "being determined" by saying that "having a will" just means not being coerced to act contrary to one's internal dispositions at time t1. According to compatibilism, being wholly determined by our molecular constitution––under the influence of the weather, magnetic currents, our diet, etc.––does not eradicate our having a will, since we are able to exercise our will precisely as the actions we do in distinction to the things we observe. I may have no choice about wanting to eat a slice of chocolate cake on the table, but my will is still intact as I am integrally involved in nature bringing it about, deterministically, that the cake gets eaten. As long as an agent acts within the parameters of its determined physical and cognitive options, the agent still has a "will" on compatibilism.
If agent B at time t2 influences agent A to act contrary to A's dispositions, then it can be said B deprived A of A's will. Oddly, this means disagreeing with and persuading other people is a form of subjugating their "will," since persuasion brings a listener to a new set of dispositions at time t2 against the original impulses of their will at time t1. If compatibilism is meant to preserve the only kind of meaningful "will" people can have in a deterministic world, why do compatibilists attempt to persuade other people of compatibilism, since doing so would suppress and eliminate other people's wills in exactly the way compatibilism is meant to preserve them? If compatibilists want to salvage my will for me as the ability to act in accord with my own dispositions, as opposed to being coerced to a new set of dispositions, then the best they can do is stop trying to persuade me against my dispositions against determinism.
Unfortunately, it is easy to conceive of a "compatibilist" account of rape: insofar as, say, the woman's legs opened and her vagina widened in response to the insertion of the rapist's penis, her actions did not "violate" her own natural constitution. Nothing in the rape violated the determined parameters of the victim, since it was always in her power to open her legs and a perfectly natural capacity of her vagina to receive a penis. Even more bizarrely, the actions of the rapist are but a whole-body form of persuasion. Typically, men and women use sound waves––and good doses of alcohol––emitted from their lungs (and home stereos) to persuade each other to have sex. Now and then, however, some people are determined by prior conditions to exercise their will in an uncoerced way to persuade others to have sex with them by much more full-bodied means.
It is a mere weak-kneed bias on the part of determinists to regard the "mental states" of an agent as more important than its somatic actions and entire physical constitution in accounting for its actions. After all, for determinists, any agent's mental states are a direct function of "lower level" somatic behavior and total physical influence. I could, by holding a gun to his head, "persuade" a man to shoot a total stranger, and he would do it even if he didn't "feel like it." I can, and often do, tell myself to take out the trash even when I don't feel like doing so. In both cases, the actions would be the result of a successful persuasion by whatever means against another agent's initial dispositions. Persuasion is as persuasion does. In the end, both forms of persuasion––seduction and rape––derive from the same deterministic matrix and both result in the same thing: the target complied with the perpetrator's influence. If every rapist is just an overly determined man, and every man is just an over-determined agent, then there seems to be little to object to in any action from a purely metaphysical standpoint. Strangely, though, for a determinist, rape is wrong, I guess. But I can only guess.