A double-check couldn't hurt

You simply can't resist. You take her by her waist and pull her toward you, kissing her passionately once again. This time, she reacts almost imediately, wrapping her arms around your neck and twisting her tongue with your. She's starting to get used to it, and you suspect she's even enthusiast about it, now. You feel her massive chest rubbing against your torso through the fabric of your shirt, and your massive boner is trapped in your pants and crying for freedom.

"I think I will have a few more inspections. And I realised I didn't even give you a grade in vaginal proficiency, which is a shame considering I will have to inspect you once a week and I need to get as many datas as possible from the beginning." you declare while kneeding her rump.

"Right." she purrs, getting even closer and looking at you in the eyes. "Plus, we still have time, I just put my clothes in the dryer after all."

Your heart is beating like crazy. You swallow your saliva and answer "Plus, you will need a shower, you can't leave this house with clean clothes while being covered in my cum. Let's go to the bathroom."

Her smile looks sincere as she follow you, one of your hands still holding her ass.

"I'm so proud of you, John!" comments your mother. "You're really taking your job seriously."

You restrain yourself from bursting out in laughter and drop your clothes on the floor while Caitlin enter the shower. When you join her, she smiles, noticing your erection. "I also didn't give you a handjob, should I do it now? You don't look like you really need help to maintain this thing up, but still."

"Absolutely! Let's do it!"

She covers her hands in soap, then grab your dick and start jerking it off while her other hand massage your back. "I can also take the opportunity to help you get clean." she say with a smirk.

"If I didn't know you so well, I would think you're actually enjoying this situation." you tell her jokingly.

She blushes and start wanking you faster. "I... maybe don't hate it... What about you?"

You marvel at her deftness. You're pretty sure it's not the first time she's giving a man a handjob, and practicing with dumbbells may have improved her skills. "What about me?"

She grabs your balls and start massaging and soaping them. "I suspect you don't hate inspecting me either."

You moan and grab her by her cheeks for yet another kiss. You can't wait anymore, you seize her thighs, wrap them around your waist and ram your soaped cock into her cunt. She yells and start waving her hips while still caressing your back. "I have to admit, it's nice to inspect you. If you weren't my sister..."

You interrupt yourself, and pretend to focus on the penetration. It's surprisingly tight in there, and softer than you thought.

"If I wasn't your sister?" she insists.

"Well..." you blushes and grab the soap to use it on her butt. "If I met a woman just like you and wasn't related to her, I would ask her out on a date..." Which is entirely true, but you have to admit being her little brother is part of what make the sex with Caitlin so hot.

She smiles at you and bites your lips. "Haaaw... Well, if a guy just like you asked me out, I would be tempted to say yes."

Your heart is now hurting, and you almost cum just hearing her statement. You remain silent, though, while your hands continue covering her rump in soap. You then start doing the same with her thighs and legs, while she takes care of your arms and shoulders. You're both still moaning and panting, and the sex is amazing, but the silence between you two is turning awkward.

"Maybe we could get a pizza and go see a movie Wednesday, right before the appointment?" you suggest.

"Absolutely!" she answers way too eagerly for it to look innocent. You instantly let out a loud roar while your cum fill her womb, and she arches backward, joining you in your orgasm. You continue pounding her and emptying your balls in her pussy, until it stops by itself. You then give her the most passionate kiss you ever had.

After all those emotions, the rest of the shower time is spent soaping each other with the occasional kiss. You take your time to make sure your gorgeous sister is completely clean, especially this beautiful rack of her, which looks like she appreciate.

You let her get out of the shower and take the opportunity to look at her ass one last time before she wraps herself in a towel, then go get new clothes in your bedroom and come back to the kitchen where your family is chatting.

"So, was this second inspection conclusive?" your mother asks with her eyes full of hopes.

"It was great!" you answer, taking the clipboard you used for Caitlin the first time. You let everybody see, as you give her a 7 in vaginal proficiency and a 8 for handjob.

"Wow, you must be so good at sex!" Dana exclaims. "To think you would be even better if your condition was cured!"

"I can't believe so many good things are happening today!" your mom adds. "You're actually extremely good at sex, darling, and nobody can deny it!"

Your big sister quietly smiles, but you can say she's proud of herself. Actually, the whole family is and, strangely, it's getting to you. Everybody will know your sister is a sex goddess, but also that you're the only guy who can fuck her ass and pussy, your job making you immune to her made up made up condition. Tomorrow looks bright for you.

"So, do you have other plans for today?" your mother suddenly asks.