It appears to be Sexual Sunday, and since I'm not feeling any of the memes on my dash (not to mention that I have a nice pile of drafts already waiting for my attention), I figured I'd throw up a headcanon instead. Mildly nsfw (hence tagged ;vices) under the cut.
The more control he has, and the less his partner has, the better he tends to like it. This means that, among other kinks, Curufin would likely find it pleasurable to subject his partner to such things as bondage, blindfolds, and otherwise sensory deprivation or restraint. He is not, however, sadomasochistic in the sense of whips and wax and the like. There is a low threshold of pain that still comes across, for him, as pleasure, such as that which is derived from biting (though not in certain areas!), scratching (lightly), and hair-pulling, but anything beyond that and the pain becomes distracting and ceases to be pleasurable.
Now, there are different ways of having control, and Curufin is subtle enough in thought and manipulation that, in certain situations, he can feel in control even in submission, or at least is willing to submit as a means to an end that he feels he cannot otherwise (or as efficiently) achieve.
There is another side to potential submission, and that is true consent to a legitimate loss of control. I do not rule this out. It might happen. For certain people, under certain conditions, or when in a certain mood, Curufin may well be persuaded to yield himself utterly. This comes most easily to him in relationships built on trust. I imagine he did submit, on occasion, to his wife in Aman, for example. Then there might be situations in which he might not have consented to the role of submissive, if it is sprung on him, but might consent nonetheless, once in that role, to the sexual activities that follow.
(Then there's just pointblank noncon, which I will not discuss here.)
