The dim light of consciousness wobbles into being, followed by a slow wash of jumbled sensation. Cold; discomfort at lying unevenly on the bare ground. The stickiness of dried blood. The terrible medical tekhne of the Hellrealms, burning in your chest like heartburn.
The mind-warping static hum, faint for now, of your captor.
People make category errors about demons, especially the ones that look like people. It's too easy to treat something that looks like a person as if it is one, even if you're treating it as a particularly wicked one. And people are stupid about sex; so of course they're very bad at properly considering the succubus.
Why would the larval instar of a demonform, you ask, grow to first holometabolism in the human worlds? Why would it interact with humans so freely? Why would it be compelled to interact with them in ways that expose them to it, so intimately, so vulnerably, in such psychological detail?
In order to understand humans, in excuciating detail, later on.
The succubyzant is larger, stronger, more obviously predatory. The primary mode of its mental powers is no longer seduction; the byzant is a crackling blast-furnace of mental power, and sheer sufficient proximity will send a man to his knees, bleeding from the nose and eyes. But death is not the fate you should fear, because the byzant's younger self spent its vulnerable years twined around human flesh and mind both, learning, always learning. It knows how to find what makes you tick. It knows how to find what makes you weep. It knows how to find what makes you break.
The primary mode of the byzant is sadism.
And when its proximity and greed for your suffering drive your screaming brain to haemorrhage, there are no finer students of human anatomy anywhere. None better at forcing unwelcome life back into your exhausted corpse. For just as human summoners can become obsessed with succubi to the exclusion of all other concern, so too in their turn can the byzants fixate on the singular suffering of one specific victim, to live and die a thousand thousand times, prolonged indefinitely for the sole purpose of their entertainment.
Hope against hope they tire of you. Hope against hope another catches their eye. The human in these fixations, no matter the instar, is always the one who suffers.
Rest now. They'll want you strong, before they begin again.