Jenny stayed at Jeff side, reassuring him until her mother entered the room, along with Jeff's new doctor. As hell's princess had guessed, say doctor was the one that had helped her formerly human mother become a succubus and helped mother and daughter stay in health since then.
Dr. Lorelei was a nice succubus, very good with her patients and always knowing how best to say what was needed to be said. She had come with all the equipment she needed for examining Jeff and, after poking and probing with both science and magic for hours, she was able give her verdict.
"Jeff, while you're technically just as human and male as you were before, you now have the same powers and need than a succubus. I believe my colleague already explained what it mean about feeding, right?" Not trusting his voice, the boy simply nodded. "Good. And as you know, like any succubus that needed an intervention to its stomach, you can't eat solid food anymore, not even after transforming. Only joy, desire and pleasure can nourish you, be it your own or someone else. You can still drink water, and even need to being human, but that's all."
"That said," pursued the doctor "you developed more demonic capability than we thought you would. You're now immortal, like demons and angels, can learn magic, have your ability to love manifest as an unbreakable mystical link, and can turn into any female animal, demons and angels include. I even found little numbs in your back proving that, thanks you the feelings you share with princess Jennifer, you're growing wings."
"To resume, you're technically still a human boy, but you have more in common with a succubus."
"Won't it cause complications?" Simultaneously asked Jenny and Jeff.
"Strangely, no. The only thing is that, for the time being, the changes currently happening in your body will make you produce a lot of superstrong succubus hormones, which mean only succubi should be authorized in the same room as you. And as you know, us succubi are all females, so until it stabilize you might feel uncomfortable in your true form. It should happen for a month at worst, but don't hesitate to use your new found powers to turn into a girl, it will make you feel better during that time."
"After, it may happen that from time to time, you feel the need to be a girl for a short while, but it won't stop you from living a globally normal life. Just make sure that you also have cloths that fit you as a girl, ok?"