A/N: Hoooo boy. Just so you know, this is all Ranger-Nova's fault. She sent me a prompt on tumblr that spawned an entire college AU in my over-fertile imagination. A college AU. I never thought I'd be doing one of those!

Anyway, it's technically an SH/SH22 crossover, but I'm not putting it in that category because crossover categories are where stories go to die. Usually. The Doctor Who, Star Wars, and Star Trek crossover categories are the exceptions, lol.

The prompt (from a list) is this: 3i - Sherbeth xD — You're overdue on this book and I want it so I'm tracking u the f*** down

==Chapter 1: Overdue==

Beth Lestrade loves being a library assistant at her university's library. The library is gloriously huge, and it feels like such a privilege to be entrusted with the welfare of all those books, all that knowledge and fiction and art… She enjoys checking out books to people and chatting with them about why they were reading what they were reading—for research or for pleasure—and she enjoys shelving the books even more. Within a month, she's got the Library of Congress system down, and shelving the books is like putting together an enormous puzzle. Even better, she is always coming across books that she might not have otherwise known about this way.

There is one torture to the job, however, and that is when a book was overdue. And she knows how these things go. If the book is not returned on time, the guilty party has to pay a fine for time served and even more money if they never return the book, but the library staff couldn't just make somebody return a book to them.

And Beth's problem, with an essay due in a couple of weeks, is that there's a book she needs on English criminal history that has been overdue for a month.

Sure, she could get the book through Amazon—she has a student Prime account—but there is no way she's spending money on a book that she should be able to access for free from the library! It's a matter of principle at this point.

She has the name of the student who has the book. All she has to do is find him.

Technically, there is no legal way for her, as a student, to find out whether or not the guilty party lives on campus, and if he does, where. But she knows a boy, Tennyson, who likes to joke that his abilities with technology make up for the paralysis in his legs. Tennyson was a classmate of hers in psychology last year, and they've stayed in touch since (nothing romantic—Tennyson has a girlfriend, Amanda, who's as good with computers as he is).

Beth calls on Tennyson's hacking expertise to find out where her target is.

He delivers within twenty-four hours.

So Beth marches down to the dorm where the kid is living, and fortunately, she doesn't need to bang on the door. The name had sounded familiar, and now she knows why, recognizing one of the guys in the lounge.

You couldn't forget this kid if you've shared a class with him, and she's had a couple, both in the criminal justice program. He's the kind of student who's whip-smart, knows all the answers, mind like a supercomputer… and then there's the whole observation-and-inference thing he pulls on everybody where he can tell you your life story in sixty seconds just from looking at you.

Beth strides over to where the kid is chatting with a friend on the couch and stops in front of them. "Sherlock Holmes?"

The boy looks up, grey eyes sharp, making her falter for a moment—not just from the way she feels she's being analyzed and assessed but also because she'd never looked him directly in the eyes before and his are gorgeous.

Then she pulls herself together, at the same moment that he's asking, "Yes, Miss Lestrade?" Of course, he remembers her.

"You have a book a month overdue from the library. We need you to return it."

Sherlock's rather good-looking friend stares at him. "Sherlock, you've had an overdue for that long?"

Sherlock rolls his eyes. "It's not as though I committed a crime, John—I just haven't finished it, that's all. I don't return books until I'm done with them."

Beth's and John's jaws fall almost in sync.

"Besides—" and now those intense eyes return to Beth—"I'd like to know how she tracked me down. I very much doubt the library's student database includes their places of residence."

"Forget tracking you down!" Beth says sharply. "You can't just keep a book out of circulation until you feel like returning it!"

"Of course, I can, and I do," comes the infuriatingly calm reply. "If I have to pay a fine, so be it."

"That's not the point!" Beth snaps. "The book doesn't belong to you—you have no right to keep it longer than your allotted time." Sherlock opens his mouth to retort, but Beth cuts him off. "Patronage of a library is a privilege. It's a responsibility; it's… it's a contract!" He raises his hand to try to interject, but she keeps going. "You make a contract in good faith with a library that you will treat its contents according to the rules! The students, the teachers, the staff—they all have a right to those books, and if you hold one overdue, you deny them that right, and you break faith with the library!"

"You're applying the basic philosophy of a civilization to a library—"

"A library is civilization in microcosm!"

He hesitates. She has him beaten and he knows it. After a moment, he tries, "I'm not done with it yet."

"You can have it back," she returns calmly, "just as soon as the person on the waiting list is done with it. That's the way it works."

His pale cheeks have taken on a tinge of color, and she has the wicked thought that embarrassment suits him. John is looking steadily at his friend, too, as if willing him to do the right thing. Finally, Sherlock throws up his hands. "All right, all right. I'll go get it." He stands. "That is, if I'm permitted to leave your sight, Detective."

"You are," Beth says serenely, not letting his sneer needle her.

"Fine," he mutters, stalking away.

John watches him go in amazement. "Well done! I have never seen Sherlock chewed out like that before."

"Neither have I, and I think it's about time somebody did it," she smirks, and holds out her hand. "Beth Lestrade, nice to meet you."

He shakes her hand firmly. "John Watson, likewise."

"You two good friends?"

"Sort of. Roommates."

"My sympathies."

John snickers. "He's not that bad, really." At her arched eyebrow, he insists, "He's not." Then he pauses. "Although, if you want to hang around a little to help me manage him when I need to, I wouldn't mind that."

Beth snorts. "Only if you're willing to pay for my lunch."

John grins. "That can be arranged."