I think it's safe to say that most people are exhillerated to a degree by "fear". In a blackmail scenario, that fear exists for both sides of the equation. For the victim, at its most basic level, it's simply a fear of having to make a decision. For the blackmailer, it's the fear the victim might be so afraid they won't make the choice they offer as "the easy option".

Lots of people will say "blackmail is illegal in real life" but to say this ignores the reality that people endure some form of humiliation every day. Very few people are wealthy enough or "free" (in body or spirit) to go through life without having to make the same types of choices that are made by victims of blackmail. Obviously I'm not saying they're the types of choices that send anybodys personal universes spinning out of orbit. Anyone who has ever had to do secretarial work, for example, will encounter tiny humiliations like this all the time. What secretary hasn't had a boss who expected her to make his coffee, for example. I make coffee, if that's what they want, but I don't always enjoy doing it.

If you escalate this idea just a little, you have the boss who likes to stand too close to his secretary/employee. Maybe guys don't understand this, but how close is "inappropriate" and when is a woman supposed to say "you're invading my space"? The answer for this is different for every woman, but it's certainly true that my idea of close and the duration I allow of that might be far longer than somebody who is more assertive than me.

Aside: IRL, I'm a lot more assertive than I used to be, but I also am probably still more "tolerant" of this type of office behavior than many younger women I have worked with. Tolerant by default rather than design.

When you have a blackmail situation like the kinds we write in stories, to be believable all they need to be is a slightly exaggerated version of the small humiliations we face in every day life like the examples above. The blackmailer must remain subtle if he/she is going to lure his victim torward making the choice they want. In the stories I write on this theme, I mostly enjoy it when the demands are just enough to steal a little bit of breath and raise the pulse by one or two beats. Anything more confronting than this -- a serious shock, for example -- puts me into such a confused state I'm incapable of making any decision at all. That's not a good headspace for the victim to be in from a blackmailer's point of view. Their fear is thus raised to a shock level also and they have to then decide whether to scrap their plan, or become more violent to go through with it which in turn takes it out of the blackmail realm and into more heavy non-consensual scenes.

The caveat to all of this is I'm well aware there are blackmailers who don't care one way or the other how they achieve the humiliation of their victims. They're no fun to play with ;-)

kinkabella

PS: The Sadean concepts of "virtue" and "fall from grace" very much are at play in blackmail fantasies. In one of his books (120 Days, I think) he makes the statement (paraphrased) "it's far more enjoyable to dominate one's peers than an inferior person." He also believed there was more fun to be had "disgracing" the virtuous whose falls from grace would always be much deeper, longer and harder than those who might not have had many morals to begin with. I like these types of themes in preference to "the haughty bitch" who is blackmailed because the haughty ones tend not to be so "innocent" and thus there can be a certain sense of righteousness in seeing them punished and humiliated.