Halvir has never craved anyone quite like this. He barely brings himself to wait until Vald has dropped off to sleep before he reaches for the enspelled manacles, pushing a quick current of energy through them and freeing the demon beneath the prince's skin. The transformation thrills him, stirring his blood as the demon's features appear. He has no use for the charmed manacles, which would keep the demon slumbering—far, far better to let the demon wake, and bind it with his own magic when it is fully present.
It's not only that the demon is strangely handsome (though sharing Prince Vald's body, how could he be otherwise?); his whole body thrums with power, the terrible force of the curse so intense that Halvir can feel it as a charge in the air. It makes him so hungry—he pins the demon beneath the weight of his spells and his body, tracing the jagged stripes of the demon's manifestation across Vald's skin, those marks of possession, that challenge. They are arguing over the prince's body every time they do this, and Halvir has no intention of being bested.
He drapes himself over Vald's back, slick fingers coaxing the demon to relent and open up for him, and this time he gives in to the possessive impulse: he bites down on the nape of Vald's neck, sucking on the flesh there. He'll leave a mark of his own on the prince's skin, and his won't vanish with the morning.