Devin is, in fact, 18 years old
Devin's memory slowly reasserted itself as he came awake. He and his mom, Janice, were spooning on the couch after their animalistic first coupling. His arm was draped over her midsection with his hand on her stomach. She was still wearing her work clothes, albeit with her skirt pulled all the way up to her waist and her panties missing. His basketball shorts were haphazardly around his ankles. In the heat of the moment, they removed only the articles of clothing that would block his cock from entering her.
Devin laid there, holding his mother. He listened to her steady breath as she slept and luxuriated in the feel of her bare ass against him. His dick had begun to stir again and he considered what to do next.
The deal was if he got straight As his mom agreed to let him freely use her body for 72 hours. He had spent weeks researching what free use meant. Granted most of that research was watching porn but he also looked it up on kink sites as well. He felt he had a handle on what he could expect this weekend but he knew all of it was theoretical. He still hadn't had an actual conversation with her about it and he didn't want to ruin his chance by crossing over boundaries that he didn't know were there.
Now that the incest taboo had been completely broken and discarded Devin knew he should wait to talk to his mom before trying to fuck her again. On the other hand, the feel of his mom's bare ass against his cock was making it expand again. He decided he was overthinking things as he pressed his rigid member between his mom's uncovered ass cheeks.
His mom let out a small purr and pushed back against his hard cock. Devin thought she had muttered his name but he couldn't be sure. He thought she might still be sleeping until her hand lazily covered his and started pushing it down toward her legs. Hint received.
On its journey downward, he felt a small patch of well trimmed hair just above her folds. He wanted to see her pussy but there would be time for that. His middle finger slid between her lips. She was slick with her own arousal and his seed. She moaned as his finger slid inside without any resistance. Devin couldn't believe that he was fingering his mom while she pushed her ass back against his hard cock.
Fully awake, Janice turned her head to look back at her son, "That feels so good, baby. Let mommy show you how to play with her pussy. Please?"
Devin wasn't expecting that last part but he decided to roll with it, "Yes, mommy. Show me."
Janice laid her hand across his, placing her fingers directly on his own. She used gentle pressure to guide his hand back up to her clit. She gasped as Devin's finger dragged across the small engorged button. Rather than continue stimulating it directly, she guided her son to go in a circle around it. Her breathing became more rapid and her moaning grew louder with each rotation of her son's finger.
He was enjoying the softness of her pussy when she erupted without warning. She pushed her head back against Devin's shoulder and growled, "Oh fuck, baby! Keep going! Mommy's coming!" Her hand fell away from his and he continued to circle her clit as she vibrated her way through her orgasm. After what felt like forever, the vibrations slowed down and became full body shudders until she finally pulled his hand away.
"That's enough, baby," she turned her head and looked toward him. She smiled weakly. "That was fucking glorious. I literally can't remember the last time I came so hard." She sank her whole body against his and sighed.
This was the first time Devin had made a woman cum. He was thrilled that he could make his mom feel like that. He basked in his mother's post-orgasmic afterglow. His own need was forgotten and in that moment he wanted nothing more than to make her cum again. And again..
After a couple of minutes, Janice sighed and rolled off the couch. She stood up and straightened her clothes. "I'm sorry, honey. I had to leave work early for the parent teacher conferences. There's some work I have to finish." She was gone before Devin even had a chance to register what just happened.
"What the fuck was that?" he thought to himself after a few seconds. He was confused, bordering on angry. Did she seriously just leave him with a hard on? After he gave her such an intense orgasm? "What happened to whatever I want, whenever I want?" he thought to himself.