Yes, so you give her a challenge.

"Yes, Master," Tiffany says, "Let me fuck your whores."
"Tiff," Candace says, showing surprising spirit.

"This one is starting to annoy me," you say, "How about you earn the right to be my main slut? I'm going to untie you and you're going to teach this one a lesson."

You begin to undo Tiffany's bonds, while Candace looks at you nervously. Mrs. Pendragon stays quiet, hoping to not get caught up in your wrath. Taking a strand of rope that was around her neck, you give your newly-submissive slut a collar- just to remind her that you're still in charge.

"What do you want me to do, Master?"
"I want you to **** your girlfriend- sexually. I want you to do whatever you can think of to make her do one thing: beg for me to fuck her.
If you can do that, I'll let you pick out a girl for you to fuck. Deal?"
"Yes, Master."

She walks over to the other side of the desk and leans down in front of Candace. She looks at her like a lioness sizing up her prey.

"We're going to play like I've wanted to for six months," Tiffany says.

She grabs the busty girl's hair and tugs. Candace stands up as quickly as possible, alleviating the pressure.
After the rope on her ankle is untied, she gets dragged over to the side of the desk that you were just fucking Tiffany against and pressed down on it.

Tiffany walks around the side of the desk and fishes through the drawers. She grabs a handful of random objects from it and comes back to the bound co-ed.

"You're going to beg for his cock, slut," the new Dominatrix says, "I'm going to tease you until you do exactly what I want."

You don't get too distracted and grab Mrs. Pendragon's hair, getting her attention.

"You're not off the hook," you say, "I'm going to fuck you. You're going to tide me over until I get a second round of chocolate pussy."

She nods submissively and doesn't put up a fight as you turn her around and bend her over. She can only watch as Tiffany tortures her presumably-now-ex-girlfriend. She is fucking Candace in the ass with a permanent marker and her pussy with a large, fancy pen.
She's moaning, but hasn't given in.

You plunge your dick into the Teacher's pussy, knowing that her recent orgasm has made her wet enough. She moans as well, seemingly-liking the feel of your cock more than she has let on.

You grab her by the hair and tug, forcing her head back. She grunts at the extra stress on her body, but also moans louder as you fuck her even harder.

Candace, meanwhile, is moaning as she is being fucked by even larger writing utensils. The sounds change, though, when Tiffany starts to spank her round ass with a metal ruler.

"Say it! Say it! Say it, you lesbian bitch," Tiffany commands.