With a little research Giles was able to explain to Johnathan and Harmony that what had happened to Johnathan was known as aspect of the demon.
"The demon's blood has conferred several abilities that it has onto you." Giles explained. "In your case, invisibility, super strength and energy absorption. Unfortunately I fear Miss Kendall may be correct and it is permanent. There's a potion that might possibly reverse your condition but it requires the heart of one of these creatures mixed into it. And the potion itself could kill you, it's usually considered a last resort, if you're in danger of dying anyway because of the aspect. You seem stable, even if you are still having some feeding issues. But the good news is, you're not a demon. You're still human, just modified. And your condition is not contagious."
"Great, so I have to live with this." Johnathan muttered miserably. "Feeding on those things, those demons?"
"Demons." Giles nodded. "Originally from various Hells. Sunnydale sits over a large rift in reality that leaks energy or at least it used to, now it's drained and there's no more detectible energy. And blood sucking vampires are gone as well. It's quite a story really -."
"Yeah, I'm sure. Do I need to avoid people? I'm so afraid I'm going to feed on Harmony again."
"You have control over it now and can choose to feed or not feed." Giles pointed out. "If Miss Kendall wishes to continue a relationship with you and you take care to never let yourself become so hungry that you can't stop yourself, than I don't see it being an issue."
"And the issue of some of them making me nauseous?"
"Avoid them and stick to the ones that don't." Giles shrugged. "You're not feeding enough to kill them anyway and are being careful to stick to ones that you know prey on humans, correct?"
"Yes, of course. I refuse to feed on people at all and the only animals I could find died and I felt awful about it. Okay, so I wasn't a vegetarian and maybe it's a little hypocritical because someone else killed those animals before I ate them, but just knowing I killed them made me feel so bad. Depressed bad."
"Than the method you've worked out for yourself is the most sound plan going forward. You can still live a full and complete life, you just have a condition that has to be consistently managed."
"You're not the only one, Johnathan." Willow smiled at her old friend. "Welcome to the Scoobies, a collection of people with superpowers."
"All of you?" Harmony asked, wide eyed.
"Oz and I are werewolves." Willow turned serious. "We're not like monsters in a movie, we're careful and we're responsible. We refuse to hurt people. And we're not demons either, just people with a condition. Like you."
"Xander and Cordelia already explained their superpowers." Johnathan stated. "And the rest of you?"
"My powers are pretty similar to Cordelia's." Buffy explained. "The only difference is someone else did this to me without asking and it can't be reversed. So I have to live with it, which is a lot easier without vampires around, the blood sucking kind, I mean. Those ones really were demons running around in dead bodies, but they're gone and my life is a lot easier because of it."
"And I can make portals." Dawn explained, hugely excited about getting to finally tell someone new about her powers. "The first time it was an accident and I ended up somewhere where there was no me and I met other versions of the Scoobies and our Xander used Magic to open the portal again and bring me home!" She chirped.
"Other versions? As in another reality?! You proved a theory that scientists would give their lives to prove?"
"Yep, she did." Xander agreed. "And she's been practicing with her powers so she can get control and doesn't accidentally end up in another reality and scare the crap outta her mother again."
"I said I was sorry!" Dawn muttered.
"And I forgive you." Joyce assured her. "And Xander thinks there may be more to her power than just portals and eventually we hope to figure it all out."
"And do you have powers, Mrs. Summers?" Harmony asked.
"She's got Mom powers." Xander told her. "And she can do amazing things with chocolate. Brownies, cookies, hot chocolate. Just wait until you taste her cooking, you'll swear it's a superpower all on it's own."
"I'm a technomage myself." Ms. Calendar told them. "It's a discipline that bridges technology and Magic "
"I'm mostly a researcher and expert on myths and folklore." Giles explained. "And I help Buffy hone her abilities and I have some knowledge of Magic."
"Wow, it's kind of amazing to think things out of myths and stuff are real." Johnathan felt like he'd entered the twilight zone. "And most people just ignore it or think it's stories. I could have lived the rest of my life never knowing and been just fine. But you know what? That thing was feeding on not just a kid, but on a sick kid -."
"And they were dying." Harmony added. "The rest of the kids knew it and were afraid. I talked to two of them just the day before this all happened. They were so scared." She leaned against Johnathan, who wrapped his arm around her.
"I stopped it from feeding on that kid." Johnathan said firmly. "If this is the price for doing the right thing then I'll live with it, because I'd never be able to live with it if I'd done nothing."
"Which makes you a hero." Harmony beamed at him. "And that's much better then being a rich geek. Which you'll probably still be anyway."