Something more conclusive.

So, writing your name on something means that you own it. That's the (insane) theory you're currently working with. You could keep marking items, asking Theresa questions, and getting similar answers, but that isn't going to give you anything you consider definitive. The most interesting piece of evidence you have for these claims is Theresa herself. She says you own her, but what does that entail?

You stand from the bed, starting to pace slowly around Theresa's room. "So. Because of my name on your arm, that means I own you, right sis?"

Theresa rolls her eyes and averts her gaze from you, but nods. "Yeah..."

"So what does that mean, exactly? What does that give me the right to do? What does that mean for you?" All pointed questions, you believe. Theresa is an intelligent young woman. You feel that she ought to respond well to you not taking things at face value.

Given her near instantaneous panic attack in the living room, you're surprised that the most she gives you now is a frustrated huff. All the more reason you're struggling to believe in any of this.

"It means exactly what it sounds like it means." She speaks clearly, akin to when she presented for projects back in high school. Sitting up on the edge of her bed, her chin is high and her eyes bore into you. It's easy to tell she's annoyed to explain this to you again, but isn't stopping herself. "You have the right to do anything you want with your property. With me. I am yours in every possible sense of the word, and cannot disobey you. My actions, my future, my very life are all in your hands." Having answered your questions, her eyes fall to the floor again, her voice softer. "I'm not thrilled about it."

Those last words sting you a bit, but you persist. You can certainly imagine how world-shattering it would be for someone to suddenly own you like a pet or a piece of furniture. It sounds like Theresa is a **** to your every whim and command. Let's test that a little bit.

"Stand up," you order. Without hesitation, Theresa is on her feet.

You point to the most open spot on the floor. "Stand there." She complies, eyes regarding you cautiously.

You rub your chin a moment, contemplating where to take things. Start small? "Start doing jumping jacks."

Theresa's brow furrows, but she quickly starts swinging her arms out, legs parting with a hop. She's actually doing it. Already getting farther than you expected to, you smirk and watch her perform the commanded action. Such a simple exercise doesn't wear on her lithe body, and her form is precise. The only part of her that doesn't seem to be in rhythm is her chest. Each jump makes those plump breasts of her bounce and shake, fighting against the fabric of her top and bra. After a minute or so, a pained expression starts to curl across her face, an audible wince accompanying her quickened breaths.

"Getting tired already?" You chuckle a bit, grinning meanly.

She shakes her head, not slowing her jumping jacks. "I'm not wearing a sports bra. My chest is starting to hurt, jumping like this."

"Oh!" You gasp in realization. "You can stop then, I'm sorry!" Theresa's posture slumps as she ceases the exercise, grabbing her tits to ease the soreness. Your cheeks turn red, watching the flesh of her bust bulge under her fingers a little. A light sheen of sweat puts a healthy glow along her skin, further drawing your eye to the shiny curve of her cleavage.

A different test, then. "Bend down and touch your toes." And she does. "Walk forward on your hands a little." And she does. "Part your feet a little bit."

"You could have just asked me to get into downward-facing dog, Gavin." Theresa chuckles softly. "Do you not know the names of the poses?" Even under your 'ownership,' it seems she still has the ability to tease you, at least a little. Even so, this very light ribbing is a cool drink of water compared to her more scathing remarks of the past.

From here, you can see even deeper down into the valley of cleavage between her breasts. They sway and wobble oh-so slightly every time Theresa adjusts her position. They look like they'd be a bit bigger than a handful, but you wouldn't know from experience. You feel something wad up in your throat again and you tear your eyes away. Why did you put her in another position that emphasizes her tits?!

"Alright, you can drop the pose, we're done." Theresa's pushes up off her hands, righting herself while her bust gives you one more tantalizing jiggle. You can feel yourself stirring in your pants, but like hell are you going to acknowledge that. You are not humoring a boner while you're with your sister.

You try to recollect your thoughts and ponder how to proceed. So far, Theresa has responded to verbal commands almost instinctively, even to her own discomfort. Physically, she seems indeed compelled to follow whatever order you give her. So, you own her bodily... but what about compliance? Will she submit to something you do, even if she doesn't like it? Glancing around the room, you think you have a good idea of what would really set her off under normal circumstances.

Striding over to her trophy shelf, you glance back at your sister and give her another command. "Sit back down on the bed, and don't get up until I say so." Without a word, she does as you say, hands resting calmly on her lap. Her eyes search for your intent as you start running your fingers along the varied surfaces of her awards. As you lift a plaque off the shelf, Theresa immediately begins to fidget. Still, she doesn't make any moves to stop you or rise from her seat, almost as if she's rooted to it.

"These trophies mean the world to you, yes?" She nods, brow knotting up slightly with worry. "All your accomplishments from high school. I've always been jealous of these, not gonna lie. You've always been smarter, stronger, and a lot more popular." You feel over a decade of negative emotions welling up in you, surfacing for the very first time. Your voice raises, tinged with a cold but seething anger. "Every single one of these is a reminder that you're the child Mom and Dad really wanted."

Staring at your sister, you're almost stunned by how composed she is. Aside from a hint of squirming, she still doesn't lunge to swipe her award from you. Her face is steady, eyes resolutely honed in on your grip on her plaque. Her breathing is slow again, quickly recovered from a little bit of exercise and stretching; nothing compared to her usual routine. She hasn't said a word since you started, neither confirming or denying anything you've brought up. Is she letting you get it out of your system? Letting you vent? Is this still a ploy to watch you dig yourself into a hole that she can bury you in later when this insufferable game finally ends?

The very thought puts a burning lump of coal in your stomach. Your whole body feels hot, practically steaming under your clothes. Why won't she stop you? Why isn't she fighting back?! This whole ordeal has gone on for too long!

You set the plaque back down on the shelf, switching it out for something more delicate; a good-sized athleticism trophy, the kind with a wide cup and a thin stem near the base. You take in both hands, gripping it tightly. "I own you, right? That means I can do whatever I want with you and your belongings, right? So if I wanted to, say, snap this in half and throw it in the trash, there's nothing you can do to stop me, right?!"

She solemnly nods, eyes flicking between you and her trophy. "Right."

With a growl, you almost feel ready to actually go through with it. "How the hell are you so calm about this?!"

"Because you ordered me to relax."

...Oh. You did do that, you guess. Back when she was still a mess in the living room. That would, in a strange way, explain why she's been so composed ever since.

That hot pit of rage in your gut is still there, but you also feel rather stupid that you might have compromised your own experiment. Drawing back your aggression just a bit, you take a breath.

"Well... I rescind that order. Act how you want."