She chooses to submit to Mary

"Fine! I-I'll submit to you, professor," Joy swallowed, and Mary grinned at her.

"Take your top off," Mary commanded, "And, from now on, no wearing a bra to my classes. And I want your shirts to make it obvious you're not wearing a bra."

Joy's hands to pull off her sweater, shirt, and bra, leaving herself topless in front of Mary and William.

"Damn, nice tits," William hummed, before he thrust into Mary and Mary moaned out as she was filled with his cum.

Then Mary moved around her desk and pushed Joy to her knees, and commanded, "Don't waste a drop."

Then Joy's head was between Mary's legs, and Joy knew what was expected of her, as she started to eat Mary out, and collected all of William's cum, swallowing it all down.

It tasted...surpringly good. Joy even moaned a bit as she swallowed it down, and her cock stirred in her pants as arousal started flowing through her. Only when Mary was satisfied that Joy had swallowed all of his cum did she pull back.

"Good girl, you're learning your place," Mary hummed, before she glanced at William, who had been watching them, and obviously enjoyed the sight, judging by how his cock was rock-hard again.

"I won't make you suck his cock, but you're going to watch me do it. And jerk off as you watch," Mary said, as she dropped to her knees, right next to Joy, "And you better enjoy it, too. I want you to cum before he does or you're only getting a fifty on your assignment."

Joy tugged her pants down and wrapped her hand around her cock as she watched Mary wrap her lips around William's cock. She had always had a bit of a crush on Mary, most of her students did, so it wasn't hard to enjoy the sight of her being so eager to suck on a big cock. Even if it was his cock.

After a little while, Joy moaned as her cock spurted out cum onto the floor, and, not too long later, Mary's mouth was obviously being filled with cum. Mary didn't swallow at first, instead turned to Joy to show the huge load of cum in her mouth before she swallowed it down, "That's enough for now, Joy. Once you lick up that mess you made, of course."

"You'll learn your place eventually," William said, as he put his cock back into his pants, and Joy glared up at him, "But at least I know you're debasing yourself for your marks now. It's a start. I think you've earned library privileges back. Oh, and, make sure you come to the game next week. Won't want to miss it."

"Yes, you better go," Mary said, as Joy ducked down to lick her cum off of the floor, "I'll flunk your next midterm if you don't show some school spirit."