Things go rather well for you and your brother, then you have to stay late at work

Over the next two days, Nick continues to impress you. He attends all the events he detailed in his little itinerary, and seems genuinely enthusiastic about the college in your discussions over dinner about what he wants to do. He's unsure yet what he wants to major in, but after meeting with the heads of both departments he's debating between English Literature or Music. You continue to hold out hope you can tempt him over to the sciences, your department in particular. The thought of tutoring your baby brother, taking him in hand and showing him the wonders of genetics as he stares up at you with eager eyes gives you a certain undeniable thrill. Still, he was always such a creative boy, so perhaps his talents would better shine in other areas.

At home, while he's not the perfect houseguest, he's far more responsible than you ever gave him credit for, keeping your living room tidy even though you have to remind him to pick up his clothes a couple times. Rather than the surly, argumentative teenager you were expecting, he seems eager to chat to you, and you respond likewise, discussing Dad, the college and his future plans enthusiastically with him. In the past it was sometimes hard to convince yourself your baby brother even liked you at all, with all the times he snapped or screamed at you when you just tried to help him. Now you find yourself skipping home from work, looking forward to seeing his cute, smiling face first thing when you step into your apartment.

There are the odd awkward moments of course, as you'd expect when a woman and boy his age start living together all of a sudden. Sometimes he seems to lose his train of thought when you're sitting on the couch next to him, and you catch his wandering gaze straying to your chest or long, muscled legs. You don't want to embarrass him so you make no mention of it and pretend you didn't see anything. He's still a teenager with raging hormones of course, so he probably can't help himself. God knows you understand how hard that is. When you were his age you used to check out every single boy you saw, even your Dad when your libido got utterly unbearable. Then there's the times you can't quite stop yourself from fussing over him before he leaves like you always used to when he was younger, adjusting his clothes and smoothing down his messy hair with your hand. Rather than being snotty or annoyed about it like you might expect from a boy his age, he always seems to end up quiet and blushing as you lean in close to his slender body. You suppose he finds it a little embarrassing that he still needs his older sister to make sure his collar is right and his fly is zipped up everyday.

In fact, the only major problem you have with him sharing your apartment is rather more your fault than his. You really didn't anticipate the difficulties it might cause a very horny New Female in her sexual prime to be living in such close quarters with a boy, even one related to her. Nick's not a child anymore, no matter how cute and small he is compared to you, and it seems like a certain large and insistent part of you is very much aware of that. It was never like this before, but now you find yourself almost constantly hard around him. Small things, like the slightest hint of his sweet scent as you step past your couch with the wrinkled sheets where he sleeps give you an almost crippling erection. You're left waddling around, awkwardly trying to hide the third leg threatening to tear through your trousers. Worse, when you allow yourself to get distracted the most naughty, dangerous thoughts keep slipping into your head. Like you'll watch him walk past and suddenly wonder if his butt is as plump and round as it looks in those deliciously tight jeans he wears, or as he chats happily about his day you'll find yourself thinking how good his soft lips would feel wrapped around the swollen head of your aching cock.

To compound the problem, you can't duck into the bathroom for the normal extended session of vigorous masturbation and multiple orgasms you'd need to calm yourself down. Quickly jerking off in the shower doesn't seem to help in the slightest, no matter how many gallons of cum you spray over the wall. You have to clean it all up even more carefully than usual, to make sure Nick doesn't notice anything amiss when he bathes himself later. Then you'll find yourself thinking about his cute, slender body, glistening wet under the shower as he washes himself, slipping in to join him and sliding your slick shaft between the deliciously soft cheeks of his cute boy butt and suddenly you're achingly hard again. It's like just having your baby brother around has sent your sex drive into upper orbit and it's getting increasingly hard to hold back these urges.

At least he's only around for one more day, you tell yourself as you sit awkwardly behind your desk on the third day of his visit, your erection pressed painfully against the side of your leg. Even while you're supposed to be working you can't stop thinking about Nick. Sometimes it's just perfectly wholesome big sister musings like wondering if he's met anyone nice at the open day events he's attending today, preferably not any of the skanky, slutty girls he seems to attract who you certainly don't approve of. But the flood of naughty fantasies just doesn't stop, and you start to wonder if perhaps the real reason why you've hated all his nasty girlfriends is perhaps because you wanted him all for yourself and your cock instead. Ridiculous, you tell yourself. You're just worried about him, that's all. And the only reason why your stupid cock is behaving this way is because you haven't gotten yourself laid in so long. As soon as Nick moves on tomorrow, you promise yourself you're going to find a nice, cute boy to fuck, by any means necessary.

Then you get the unwelcome announcement that one of your colleagues has taken ill, dumping a whole mountain of her work in your lap. Rather than heading home to your baby brother and a nice chat over supper about his day, you now have to stay at the office marking sophomore exams. Annoying at the best of times, but now you're missing time you could have spent enjoying yourself with Nick. Still, it has to be done, so you send your brother a quick text telling him you'll be late and he can order in some food if he gets hungry, with a gentle reminder that this still means you'll want to hear what he's got up to today when you do get back. Just to make sure he's being productive with his time and not getting led astray by any slutty freshman girls.

He responds a little later telling you he'll be fine, and you settle down to work in your quiet office. A shame you're going to miss this chance to spend more time with your brother, but you've already promised yourself he'll be seeing much more of you from now on. After all, he's got the grades, so why wouldn't he come to the same college where his older sister works? Just so you can keep an eye on him and make sure he keeps being a good, well-behaved boy, of course.