While Alan and Susan were having fun in Alan's room, Suzanne and Katherine were busy "greeting" each other some more downstairs in the living room. They knew that Alan and Susan would be gone for a good while. They focused on each other's pussies and clits.
Lately, it wasn't unusual to take a half an hour or more of extremely vigorous and talented sucking and licking before Alan would finally give up a load (given that there'd be lots of kissing and groping and resting going on as well), so the two of them figured that they had at least that much time. They all knew about his PC muscle control now, and they both blessed it and cursed it. They truly enjoyed cocksucking for long periods of time, but it was downright exhausting on the jaw muscles sometimes.
Just seconds after Alan and Susan had gone upstairs, Katherine went upstairs herself to change her outfit. She returned quickly, naked but carrying a white shirt and a pair of green shorts that she had customized. Katherine explained that her new outfit was for "visual stimulation," showing off her shorts before throwing them and the shirt on a nearby chair, eliciting a thumbs-up sign of approval from Suzanne.
They sat on the sofa next to each other. Suzanne kept her dress bunched around her waist. It didn't block any vital access, but it allowed her to quickly cover up, just in case. She'd retrieved a sheet from the laundry and thrown it over the sofa while Katherine was changing, to catch most of their cum and sweat.
They figured that when Susan came back they'd have a few moments to hear Alan's door open and get decent, including hiding the sheet, before she could walk down the stairs to where she could see them. If they did get caught, they knew it wouldn't be the end of the world, but it still wasn't a good idea for Susan to see them making out naked just yet. That definitely would trigger a big setback in Susan's sexual progress.
Before long, they got into a sixty-nine and really went after each other. They munched each other to orgasm seemingly without ever tiring.
For nearly an hour, they hardly moved from their sixty-nine, because both of them had penis-starved pussies that needed pleasing, and satisfying any other sexual need was far down the list. Dildos or strap-ons would have been perfect to give both of them that "fucked by Alan" feeling they craved more than anything, but for once neither of them had any toys handy.
In the middle of their mutual licking, an important thought came to Katherine. "Oh! Aunt Suzy, I've been meaning to ask you. What's up with Mom?"
"What do you mean?" Suzanne asked.
"I mean, is she turning bisexual or something? You know that this morning she and I kissed, on the lips, and not just for a few seconds! It was TOTALLY HOT! And Gaawwwd, I was able to feel her up all over! And then, this afternoon, I was able to put my fingers in her pussy and her asshole, and she didn't complain!"
"Oh, really? Tell me more!"
"Later. Right now, I'd rather lick than talk. But I just want to know what the deal is!"
Suzanne sighed with frustration, because she knew she'd have to stop enjoying the taste of Katherine's pussy for a minute or two in order to give that a proper answer. She sat up, forcing Katherine to sit up too. "It's complicated. You really want me to explain?"
"YES! This is soooo key! I was actually gonna call or visit you earlier to find out, 'cos I'm so dying to know. But then I remembered how you don't like anything sexual going on at your house. And then, well, we got kinda distracted." She giggled, looking down at their bodies which smelled of sex. "But if she IS bisexual, do you realize how MASSIVE that is?!"
Suzanne chuckled. "As a matter of fact, I do! And I'm just like you: I think it's just about the best news ever, especially since it IS true, and she IS becoming bisexual!"
"NO WAY! REALLY?!"
As soon as Suzanne nodded gleefully at that, Katherine attacked her with a searing kiss with such intensity that she pushed her back down. Then she pretty much went wild over her for the next few minutes, until her energy started to flag.
Once Suzanne was able to speak again, she said with amusement, "I take it you like that idea. It made you sprout at least eight extra arms, because your hands were all over me!"
Katherine giggled at that, and fondly caressed Suzanne's ample globes with both hands. "Hell, yeah! Aunt Suzy, I love you a whole hell of a lot. I'm unbelievably psyched that we can do what we're doing right now! But to be able to do that with MOM, well, it's even MORE exciting!" She frowned with worry. "I hope you don't take offense."
Suzanne quickly put her worries to rest. "Relax, I know exactly how you feel. There's something about her being so prudish and innocent that makes her new sexual awakening that much more exciting. But, to finally answer your question fully, your mom Susan is primarily all about Alan. That's become... well, I don't think it would be an exaggeration to say that having sexual fun with him has become the most important thing in her life. But she also loves me and you about as much as one person can love another, and she's starting to realize that she can express that love physically. So, yeah, she's becoming bisexual. I'll bet that, before long, we'll see her getting intimate with other women she doesn't even know that well, like Brenda, as long as it can somehow be linked to sexually serving her son."
"Cool! Oh, Aunt Suzy, you have no idea how happy that makes me feel. On top of that, I'm here in your arms. Everything is so damn GREAT!"
Suzanne ran her hands down Katherine's back as she replied, "Tell me about it! I've been lusting after your mom since you were in diapers. But take it slow with her, okay? Give her time to get used to these big changes in her life."
"Okay. Drat. To quote the most squeezably lovable mom on Earth, 'Oh, poo!'"
Suzanne drew in close for another kiss. "Yeah, well, if it's any consolation, you can burn off some of your lusty energy on me."
Katherine replied with more passionate kissing. Before long, they were again in a sixty-nine position.
Eventually, they heard some loud female screams upstairs. Then they heard some more, and still more.
Katherine was dying of curiosity. She knew Alan had to be doing something to Susan that was making her cry out in ecstasy, but she wanted to know the exact cause. So she politely pulled away from Suzanne, explaining that she just had to peek in upstairs to see what was happening upstairs. That's why Katherine first listened at the door and then actually walked in on Alan spanking Susan.
Because Alan had shooed her away relatively quickly, Katherine came back downstairs, still naked, and resumed having sexy fun with Suzanne. But the mood had been broken by Katherine's departure, so they simply sat and French kissed for a while. Between kisses, Katherine told Suzanne about the spanking she'd witnessed.
Eventually, they heard a door upstairs open and shut. This alerted them to make themselves presentable. Luckily, they still had their clothes handy and had been acutely listening for any sound, since Alan and Susan had been gone longer than expected. Not having to wear bras or panties allowed them to get dressed in a hurry. They hid the remaining evidence by stuffing the wet sheet underneath the sofa.
As it turned out, Suzanne and Katherine had plenty of time to dress and make themselves presentable before anyone came down the stairs, because in fact neither Alan nor Susan came downstairs for a while.
