An ancient ritual

"Wouldn't dare?" Nova asked rhetorically. "Of course I'd dare. See, Grandma left me a little something before she passed, a note that was enchanted so that I couldn't read it until today."

Nova could tell that Marina wanted to stay silent, but her curiosity got the better of her. "What did that note say?"

"That there's a ritual in the Willard bloodline, one that requires some very particular circumstances to perform. Grandma never told Mom about it, which is how she didn't know to avoid creating the conditions to allow me to perform it."

"And what does that ritual entail, and what does it do?" Marina couldn't help but ask.

"I'm so glad you asked," Nova said, waving a hand to close the door behind her telekinetically. "See, it requires that the second child born into a generation also be a woman, and that she be born within a year of the first child, and that she be said first child's full sister. Which you are, if only just on the second one. Which means I can perform it."

"Nova, if this is going where I think this is going, even you wouldn't contemplate it."

"What, you think I'm going to sacrifice you for greater power or something?" Nova laughed. "Marina, you're still my sister, even though I intend to use you to test my powers. Doing something like that, I promise you, would be anathema to me. I want to have fun, not go that far. No, I'll just need a few things from you to perform the ritual, and then Mom won't be able to do a single thing to me."

"What... things do you need from me?" Marina asked, scooting further back on her bed.

Nova pointed a finger at her younger sister and froze her body in place, then crooked it to drag Marina back toward her. "It's quite simple, really. I just need three fluids from you, and nothing says I can't use magic to get them."

"Three fluids?" Marina said, her head still functional. "Nova... no, you can't even be thinking of that, I'm your sister!"

Nova gestured and Marina's clothes vanished from her body, reappearing in a neatly folded pile on her desk. Marina's face scrunched up as she realised that she couldn't cover herself, and Nova manipulated her body to **** her sister to present herself as much as possible.

"Now, the first thing I'll need is a little blood," the newly fledged witch said, holding up her index finger. The nail sharpened to a point, and she pricked Marina's thumb. Letting a drop of blood well at the tiny wound, Nova sensually licked it off. "Mmm," she said, putting a hint of arousal into her voice because she knew it would creep Marina out. A quick application of basic healing magic meant that no evidence was left.

"You're disgusting if this is going where I think it's going," Marina said.

"Disgusting? Marina, I just want to have fun and not have Mom get in my way. And this is how to do it. Assuming Grandma wasn't lying to me, of course. And if she was, well, I've still got enough power to make sure that you'll never tell." Nova returned her nail to normal before using it to tap Marina's breast and inject magic into it.

"Ugh, Nova, did you just..." Marina's eyes flicked downward as Nova lightly squeezed her nipple, and she couldn't help but let just a tiny moan of pleasure out as the witch gently suckled at it to get just a single drop of milk, her magic having made her sister lactate.

"Now, I could do this last by manual stimulation, but given your mindset about all this, that would take quite a while," Nova said. "Thankfully, magic is perfectly good for that as well." Nova reached down, running her finger slowly across Marina's labia and lingering on her clit. Instantly Marina became aroused despite her fear, her pussy lubricating even though it was her sister providing the stimulation, Marina's mind and body unable to resist Nova's magic.

"Don't worry, sis, I won't go quite that far," Nova said before licking Marina's juices off her digit, after which Nova let out a moan of ecstasy as power flooded into her.

Still frozen in place, Marina asked, "So are you going to tell me what you had to be a massive pervert to your own sister to do?"

"Simple. That was a little ritual that unlocked all of my powers, right here, right now, and all the knowledge I need to use them. And it made me completely immortal until I decide to pass on. I could get hit by an airplane and it would just crumple around me. So instead of Mom being way more powerful than me, I'm way more powerful than her now." Nova gestured at Marina again, unfreezing her. "And the first thing I've done is alter your mind to make sure that you can't ever tell her what I've done, or am going to do with you."

"Nobody should be that powerful, especially not someone like you," Marina said.

"Should? Maybe. We don't live in the land of 'should', though. We live in the world as it is, and in this world, your big sister might as well be a goddess."

Marina scrambled back again as Nova morphed her clothing into a low-cut, midriff-baring bustier, skimpy panties, and knee-high buckled boots, all black, looking every bit the stereotypical slutty witch.

"Now, power and knowledge are one thing, but experience is quite another," Nova noted. "So as much as I'd love to give myself a hot body right now, it's possible I'd mess it up. Thankfully, when it comes to using my powers on anyone else, it's fully reversible. And you, dear sister, just so happen to be 'anyone else'."

"You really are a pervert," Marina said, finally getting over her shock enough to cover her breasts and crotch.

"I'm a pervert with nigh-unlimited power and no consequences for my actions," Nova said. She waved a hand at Marina, and her sister once again lost control of her body, whimpering as she was lifted off the bed and suspended in midair by Nova's irresistible magic. "So let's see, a small test first."

Hair gushed from Marina's scalp as Nova desired that it grow, and grow it did, dropping from its previous shoulder length down to her butt, then her knees, ankles, and finally coming to rest when it began to pool on the floor despite Marina hovering a few feet above. Nova levitated into the air as well, bringing herself to eye level with the other woman.

"And now to reverse that," Nova said, and the hair sucked itself back in, rapidly restored to its former length but going further, up to Marina's neck and then finally settling into a pixie cut. From there it cycled through various colours before Nova settled on a blue to match Marina's eyes, and finally it grew back to its original length.

Nova spun Marina around so she could see herself in her mirror.

"People will notice that, you know," Marina pointed out. "Did you at least leave my roots as they were so that it will just look like I dyed it?"

"I assure you this is all natural," Nova said. "Or maybe all supernatural. But even if people notice, not even Mom will think there's anything strange about it. I could give you breasts that overflow your lap and nobody would think anything of it."

"You wouldn't," Marina said again, though with each protestation she sounded more and more resigned to being nothing more than the first of her sister's many toys.

"That big? Probably not," Nova agreed. "It would be a pain to do the necessary detail work on your anatomy, never mind setting up a field around you so that you don't bump into everything, and I'd feel responsible for ensuring you have proper clothing, and all that, since you'd have to get everything custom-made otherwise. I'm a pervert, Marina. I'm not heartless."

"Some way you have of showing it," her sister grumbled.

"Of course, that doesn't mean I won't do it as a temporary matter. Or maybe I'll try something else first," Nova mused.