Katherine immediately stripped off the rest of her clothes and sat right next to Xania and Alan. At first she didn't know how to join in or what Xania would allow her to do.
But then Xania said to her, "Here, if you want to get knocked up so bad, then let him cum in you." She raised her soaked and quivering pussy from Alan's ever-ready cock, then used both hands to position it for Katherine to climb aboard.
The good "doctor" repositioned herself so Alan could suck on her nipples while he pumped up into his sister. Xania refrained from touching Katherine sexually, though she very much wanted to. Suzanne had given her strict orders to not get sexually involved with either Susan or Katherine. She'd already gone pretty far with Susan with all the "California kissing," but she didn't want to push her luck any further with Katherine. Besides, she was having plenty of fun with Alan.
Alan fucked his sister for a few minutes before taking a "strategic break" to rest his overheated erection. They used the pause to change positions.
Xania said, "Enough kidding around. Now's the time to put a condom on for real."
Katherine said in a sad voice, "I'm on the Pill and I'm wearing a diaphragm. He makes me. So unfortunately he won't be knocking me up today, condom or no condom." She added with hope and desire, "Although there's always a small chance I'll get lucky..." She got up on the couch so her ass would be positioned high in the air.
Alan got behind her so he could fuck her doggy-style.
Xania asked Katherine, "So you're gonna let him do you bareback?"
Katherine smiled from ear to ear. "Yeah. It feels soooo much better!"
"Do you mind if I help guide him in?"
"Please! Be my guest!" Katherine thought, Boy, this day is sure turning around in a hurry. Xania is way cool!
Feeling devilish, Xania positioned Alan's cock so the tip was resting against his sister's labia. However, she said, "Hold on. Let me make sure he's good and lubed up first." She bent over and licked his pole from top to bottom. She came within a fraction of an inch of putting her tongue against Katherine's wet slit.
Katherine was finally in a charitable mood, knowing that she was about to get a great fuck. She giggled. "That's hardly necessary."
"Still, it's best to be sure."
There were laughs all around while Xania slathered Alan's cock with her tongue, because all three knew how very unnecessary that was. Alan's boner was thoroughly coated in a mixture of saliva, pussy juice and pre-cum.
Xania jacked him off and licked him, then slowly inserted him into Katherine. As if she wasn't busy enough, now that she was more calm (because she wasn't in the middle of getting fucked) she took the opportunity to lecture Katherine, "Did you notice how unselfishly I'm handing Alan over to you? I'm doing that to make a point. Given that he has sex with so many women, you need to be similarly unselfish or you'll eventually become consumed with jealousy."
"UNRNGH!" Katherine wasn't disagreeing, she was just grunting loudly as the widest part of Alan's cockhead pushed into her.
Xania kept on with her licking, stroking, and talking. "As his sister, you'll always have a special place at the top of his list, along with his mother. The incest taboo alone is a great lure he'll never tire of, and your bonds of love are deep."
Katherine spoke loudly. "I'm listening, but push it in deeper! Faster!"
Xania did push Alan further into Katherine, but she also said, "Hold on. Can't I have at least a couple of inches to play with? Your brother has a very remarkable cock."
"Don't I know it! But push! Puuuush! Then lick his balls if you must."
"Ah. Good idea." She pushed another inch or two of Alan's great thickness into Katherine.
"AAAAIIIIEEE!"
"Ssssh!" Xania chided. "We don't want your mother to hear, do we?"
"Drat!" Katherine resolved to stay quiet, but it was almost torture to do so, especially when Xania pushed him in the last inch or two, causing him to completely fill her up. The horny sister sighed with supreme satisfaction.
Xania got right to licking Alan's balls. She figured she wouldn't have much time to do that, before their fucking rhythm made keeping her face that close too dangerous. However, at that moment, Katherine was still adjusting to Alan's girth. Despite all the arousing distractions, Xania kept on with her advice. "Maybe if your looks were average you'd have a problem, but you're stunning! You're a sexy fox, and you have the big breasts he loves. So don't worry. And by being unselfish, you yourself can reap the rewards, as this threesome illustrates."
"Wow! That's a pretty cool lesson, I gotta admit," Katherine said casually as she pushed herself backwards onto her brother's stiff member. "Maybe coming to a psychologist wasn't such a bad thing after all."
"Coming IN a psychologist isn't such a bad thing after all, either," Alan blurted out loud.
Everyone laughed, helping to lighten the mood.
Xania was pretty impressed with herself as well. The entire session with Katherine and Alan together was something she'd made up on the spot, not something Suzanne had coached her to do. As she watched the siblings thrust back and forth in a good rhythm, she thought, Hot sex and a good lesson on jealousy for Katherine to think about! What a fun day this has been. If there was ever such a thing as a sex psychologist, I think I'd be pretty damned good at it.
Katherine and Alan soon reached a good fucking rhythm. Xania sat back and just watched for a while, since she didn't want an ass or crotch slammed into her head.
A few minutes passed. Alan continued to fuck Katherine doggy-style. Xania reengaged, draping herself all over him, generally kissing and fondling him while he did the same back to her. She was careful not to touch Katherine too much though, since she didn't know how the girl would react if she did.
Eventually, Alan and Xania had to stop necking because the intensity of the fucking was increasing and he was having great difficulty breathing. Xania kept right on kissing him elsewhere on his face, as well as kissing and licking his neck. She also made sure to keep her big globes within easy reach so he could play with them.
After a while, she got around to licking one of his ears, and that gave her the idea to whisper in his ear. "You know, when Suzanne asked me to see you all as a personal favor, she warned me. She said you were a nice guy, but between my looks and your needy cock, odds were good I'd wind up on my back with your fat boner balls-deep in my cunt! I thought she was just joking, but it turned out she was spot on."
As she playfully nibbled on his ear, she asked teasingly, "Are you going to add me to your harem? Do you want me to be one of your fuck toys? Where do I sign up?"
Had he thought that she was at all serious, he would have jumped eagerly on that suggestion. But it was clear from her tone of voice and general demeanor that she was just trying to arouse him with provocative teasing.
With all the fucking and fondling going on around him, not to mention the way Xania was licking and nibbling at his ear, he wasn't expected to give a serious answer, so he didn't. He just muttered, "I wish!" and concentrated on slamming in and out of Katherine.
Katherine thought, She is just joking, right? She'd better be joking! But even if she is, I'm sure she'll be back for more at some point. Everyone he fucks wants another round.
After another minute or so, Xania said, "I can see that your fucking is speeding up. Soon one or both of you are gonna cum. But Katherine, I understand you have a football game to cheer for. If you leave soon, after you have a nice cum, I think you'll be able to catch some of it."
"Oh, right. Thanks!" Katherine was rather hoping for more "lessons" from Xania, especially if they involved more sex with her brother. But then she thought of her commitments; the other cheerleaders were counting on her. She looked over her shoulder, then asked, "Big Psychologist-slaying Brother, could you cum quickly for me? I've gotta run, and I want to feel your baby juice sloshing around inside my cunny during the long drive home."
"No prob, Sis. I'm totally ready to blow anyways." He fucked her at an even harder and faster pace.
Xania had just changed positions, opening up new fondling opportunities. So, at the same time, he stuck fingers in Xania's pussy and asshole, sawing her holes in time to the overall fucking pace. He wanted her to have a good final orgasm too.
Within another minute, all three of them were on the verge of cumming. Alan usually felt the need to prolong his climax as long as possible; he saw having to cum as a sign of defeat, as it usually meant the sex session was over. But he'd had so much sex over the course of the day already that he was looking forward to some rest and recovery time.
He thrust into his sister's pussy a few more times before he let himself go with an exceptionally loud grunt. After having used a condom so many times that day, it felt especially great for him when he shot his seed bareback straight into his sister's pussy.
As soon as Xania and Katherine realized that Alan was cumming, they let their climaxes overtake them too. Katherine's climax caused her pussy to tighten and clench so much and so unpredictably around Alan's erection that it seemed to double his pleasure and squeeze even more cum out of him.
The three of them each let out fairly loud screams as their passion overtook them. It occurred to Alan that Susan was still sitting in the waiting room next door. He figured she'd have to have heard the screaming, and he wondered what she'd think about it. In any case, it was too late now to try to remain quiet.