Give her a facial, then continue from there...

Realizing that with your increased capabilities, you could pretty much control when, where and how much you came, you decided that the only thing hotter than Nurse Fuckslut (as you've come to name her in your mind) would be cum-covered Nurse Fuckslut. You grab her hair and throw her off of your cock.

Seeing you in your demon form, the lust in her eyes was now battling the growing fear in her heart. Still, with the grip you had on her hair, she could not get away lest she risk going bald. Holding her in front of your mighty dick, you fire your demon sperm into her face. Shot after shot covers her cheeks, nose, eyes, forehead, mouth and her hair until everything above her neck is nothing but a gooey white mess. You still retain your hardness though, and she apparently still retains her lust as she proceeds to swallow all the cum that's landed on her face. She nearly orgasms from the consumpsion of your jizz alone. With a smile, you begin your next phase.

Having a good sense of her oral skills, you quickly turn her around and rip off her undergarments, leaving her only wearing shreds of her uniform and her pussy completely exposed. Iris was at this point panting for your cock, and you respond in kind as you thrust forward in one stroke, completely filling her and stretching her out to the max. You start to fuck her, furiously impaling Iris over and over again, her moans and cries of ecstasy echoing through out the hospital, yet strangely unheard (you could thank your soundproofing magic for that, wouldn't want to alert any others to your presence). With your phallic tail, you begin to roughly take her ass. She starts to tear up at the painful penetration but soon back into her throes of moaning and **** lust.

As a final trick, you expand your dick until it pushes up and past her cervix, making her eyes nearly pop out of her head as pain and lust overtake her. Double penetrating her like you are, you cannot and do not want to last any longer, so with a deep and bellowing cry, you release fully, directly into her ass and her womb. With your orgasm comes hers and with a matching cry, she releases her juices and passes her soul to you for nourishment. With her soul gone, Iris changes from a rather ragged but kindly nurse into a hellsent succubus, bent on sexually temping mortals to their doom. Her skin takes on a malevolent shade of red to match her hair, her eyes shift back to their green color, but are much more expressive, her breasts enlarge to unholy perfection, while her ass shapes up into a perfect bubblebutt. Her tailbone extends into a replica of your own phallic one, meanwhile her upper back explodes with dark wings and her nails sharpen into claws. In short, she has fully transformed into her succubus form. With that taken care of, you can begin the next phase of your grand scheme...