Take charge of the situation.

You push the door fully open and march inside. Neither Nicholas nor the girl notice you right away so you take the opportunity to assert yourself.

"So, this is what you do while I'm at work." You say dryly. "You couldn't have scored anyone hotter than this? God, that's embarrassing."

Two shocked faces turn suddenly to face you, both flushed and horrified. Nicholas pulls out of his red-faced slut with a wet sound. "Mindy! Shit, I— ah... I can explain this." Words fail him. He was never particularly good with them in the first place, then his face registers confusion as he takes in the sight of you. "Wha— what did you do? You look real good!"

You're clenching your fist so tightly around the reality stone that it hurts, but you refuse to let anger control you. "Shut up, idiot. I'm not looking for excuses and you can't flatter your way out of this one."

The girl moves to slide off the bed and cover herself, so you focus on her. "Don't you move, sweetheart. You will stay right here like a good little whore, wet and ready. This is why you came here, isn't it? To be a naughty little whore? Own it."

She whimpers and returns to her hands and knees in the middle of the bed. Her clean-shaven pussy is soaking wet, and the scent of her fills the small bedroom. She may be somewhat plain to look at, but something tells you she's wild in bed.

Nicholas stares at you, somehow even more stunned than when he was caught red-handed. "Woah, what's with you, Mindy? I've never heard you talk like th—"

You glare at him, still deciding what exactly you want to do with him. "You will not speak to me again unless spoken to. You are in very big trouble and you are going to do everything I say until I forgive you."

His mouth snaps shut and a look of horror crosses his face.

"Good boy. Now, don't you know it's rude not to finish what you started?" You gesture to Skinny, still presenting herself on all fours, somehow even more wet than before. She's actually dripping onto the bed. That's actually super hot. "Fuck this bitch. Show me what you were going to do if I hadn't caught you."

Nicholas's cock has remained fully erect this entire time, which you note is fairly impressive. Usually he needs a lot of help to keep things going but some combination of your new look and total power over him seems to be really doing it for him. As he turns back to Skinny and plunges his rod back into her, she shudders with delight.

You walk around to command her attention while your boyfriend resumes fucking her. She looks at you like a cornered mouse. "How much is this dipshit paying you, huh?"

She looks away, her entire face bright pink with humiliation, but returns her eyes to yours when you catch her chin with one cupped hand. "Uh... he's not paying me."

Your eyes widen in mock surprise. "Oh, so you're not even a whore, you're just a common slut." You focus hard on the idea of her being an always-horny, sex-hungry nympho slut with every fetish and kink you can think of. "You are a total slut. Look at me. That's what you are, and what you'll always be. A ****, needy, submissive little slut, and you belong to me now. Forever. And I'm going to make you pay for fucking my boyfriend."

She closes her eyes as an orgasm rips through her, a strained moan hinting at the sheer intensity of the experience as her arms collapse and she falls forward onto her face.

You let her go and step back to watch. It doesn't even bother you anymore, Nicholas fucking this bitch. She's your bitch now, same as him. They've had a taste of the power you command, but you're only getting warmed up. Of course, watching the two of them helplessly comply with your twisted instructions is starting to really turn you on.

There's still so much to do with them but first, you may want to blow off some steam, yourself.