Simple Harmonic Motion - in cases of simple, ideal periodic or oscillating motion, the restoring force is directly proportional to displacement. Only valid for small displacements, though. Nothing is ever certain

ONE

When the bell sounded to end second period, Seth Castle shouldered through the East Building towards the band room, moving quickly and quietly without seeming like he was in too much of a rush. In thirty seconds, was in and out, stowing his AP Physics book and picking up his gym uniform, and then made a bee-line for the red rhododendron outside. It may seem a bit obvious to snoop while hiding behind plants, but Blake and her friends had their second meeting of the morning in behind the band room, within earshot of the rhododendron. It was a charitably tall and bushy rhododendron, all the better to hide a varsity basketball player.

There was not much about the ebb and flow of social relationships at Boulanger High School that Seth Castle missed. He had an incredible memory, was incredibly nosy, and had an incredible desire to know anything and everything about his peers. It was comforting to know these things, and to understand the people that went to his school. Seth was a sophomore who took AP Physics B and AP Calculus AB, a boy who loved science and math and loved putting answers in boxes.

Seth Castle was acutely aware of several universal truths. He and everyone around him lived in accordance to the laws of physics and mathematics – that was undeniable. A is A. Existence exists. There were forces that acted on everything at all times, and math worked. That was one truth. Seth contrived to know as much about his surroundings and his classmates as he knew about himself. Another truth was that if he were to (1) skip his medication, (2) wear white socks, (3) touch somebody wearing the color orange, the day would be ruined.

Seth Castle, as a high school student himself and as a keen student of Hollywood teen movies and TV and social media, was aware of several other truths that governed high school. As he stood behind the rhododendron to get one step closer – figuratively, of course – to certainty, he saw one of them play out:

When popular girls were huddled together giggling and whispering and one of the girls is at the center of it, it was usually about a cute boy or a completely hideous and socially oblivious girl.

A puffy red flower covered Blake Xiong's head from Seth's view, but he glimpsed another girl, probably Cherry from the way she dressed, shake her by the shoulder. They were teasing her, the richest and most popular of their clique, who set the trends at their school and was class president, and she was crying out in that bell-like voice about it. Of course it was about a boy.

There was one thing left to do – and something Seth almost never did – to complete that all-important character summary of Blake Xiong in Seth's mental dossier of sophomores in the Boulanger High School band. He crossed over to the senior parking lot, stood up a little taller, and walked casually towards the gymnasium, directly within view of the band room and Blake's girls.

And Blake herself, of course.

And now, from the cluster of girls: "What's the worst thing that could happen? Just do it, Blake!"

The B-word – Seth immediately stared at the ground, willing one foot in front of the next. One sock was lower than the other, and it was bothering him. The girls were chattering again, and now he was almost close enough to see that Blake was actually looking at him. She made a bigger deal about acting natural than he did, turning away with a quick change of topic, and that was that.

And that was that. The matter of Blake's crush was one that most of the popular sophomores wondered about since the beginning of high school. Blake Xiong was the mythic pretty, rich, popular, smart girl who was always asked to dances, but always chose to go alone. Something about strict parents, but she had always claimed that she was hoping someone else would ask her. A rumor from within her own group was that it had been the same guy, and that after a year, she would try to make a move. It was, after all, the twenty-first century.

Seth successfully vanished for the rest of break and sat with his back against the gym's stucco walls to count the cones on the pine tree by the baseball field. People came and went without paying attention to him, and that was one of Seth's favorite truths about himself and his high school. If he wanted to, he could be completely invisible, a silent fly on the wall who counted pine cones and eavesdropped on the furtive conversation next to him.

Not today, though. The pine cones seemed to go up and down in number as Seth rifled through his facts about Blake with new urgency.

Seth contrived to know as much as he could about everyone, every clique at school – it was in this particular clique where mention of him, Seth Castle, was not impossible, but even likely, and it was all due to Blake. Blake Xiong, ringleader of the band and colorguard clique, also played the saxophone. She used size 3 Vandoren reeds for marching band, and 3.5 for jazz band. She played flute in concert band. Seth saw her often at band functions, and his very own cousin was part of her posse, starting from the very beginning of freshman year band camp. She was sophomore class president, vice president of Model UN, and a member of the Red Cross club. She was student of the month last April. Blake was smart and very pretty, popular and very wealthy. Her grandmother drove her to school in a new Mercedes, and when she bummed rides from her friends, it wasn't bumming rides. It was considered a great privilege to drive her home. This all Seth knew, all gleaned from band, English class, and gym, which they shared since freshman year – and, of course, gossip and rumors, hearsay.

They were coming towards the gym, and when Blake looked over in his direction, he darted inside. The truth was that for the past year, he'd accidentally caught her eye a few times, a few times too many, in fact. In all the movies he saw, accidental eye contact was only accidental eye contact the first time. She'd borrowed his pencil a few times during their acquaintance – she'd always returned them, but there was a certain implication.

Seth successfully vanished, and if he could disappear into the boys' locker room before anything else happened, he would be golden. Blake and two of her entourage were in gym class with him, but they were the quieter ones, more concerned with giggling over inside jokes than gossiping loud about boys, potentially Seth Castle.

When Seth felt a tap on his shoulder, he nearly jumped out of his skin. "Plastics on your tail?" called a girl behind him. Seth turned around and greeted one of the only people he talked to at school, Maggie Shen, who he secretly thought only hung out with him because he was on the varsity basketball team. She played a lot of basketball, but was rather short – she was much better at Call of Duty, and even better at painting furniture, and Seth figured that she would continue deluding herself into thinking she could make varsity unless someone told her otherwise. She also had a penchant for calling Blake and her cronies 'Plastics,' which Seth suspected was homage to Mean Girls, which Maggie had only recently watched, at his request.

Seth didn't believe that Blake and company bore any real resemblance to Regina George and her company –they were mostly wealthy, catty, and conniving, and those were qualities that most of the most popular cliques in each grade level shared. Blake, however, was no blonde, and she seldom wore pink. She thought it was tacky.

Maggie kept talking. "You know, Seth, Rocky told me that he's seen her at a caffeine addict's anonymous meeting, she drinks so many Red Bulls." The bell rang and Maggie waved. "See you in class, Castle!"

Rocky was another one of Seth's friends, one of the only people in the school that was taller than him. He was six and a half feet tall, twenty pounds underweight, on the varsity basketball team, and while Seth didn't know that he was addicted to caffeine, he did know that Rocky had a Starbucks Gold card. He told more tall tales than truths, and was a ginger – Seth distrusted him on principle, and went to the locker rooms still wondering if a twelve step program for caffeine even existed.

Rocky was not in Seth's gym class, but, unfortunately, the absence of one chatty basketball team member was filled by scores of rowdy JV jocks, and plenty of vapid girls to fawn over them. Gym class was taught by the somewhat overweight JV basketball Coach Randall, which meant that Seth, should he ever feel the inclination, could literally get away with murder in class. Boulanger High School, like so many American high schools depicted in film and television, worshiped athletes. Seth was content to be the star of only one sport, and luckily for him, the basketball season had not yet begun.

Blake and her tiny little sidekick Bailey, another stick-thin Chinese girl with a high-pitched giggle, were completely awful at basketball and most other sports – no hand-eye coordination, no particular motivation to try. The boys teased them with flirtation as their motive, and the girls that liked them sucked with them to gain their favor. Blake, on the other hand, giggled and swatted them away like flies.

As much as Seth thought the Plastics were very much like the popular girl cliques in every teen movie he had ever seen – and he had seen a lot – Blake wasn't that bad. For a popular girl, she seemed rather decent, although she had a distinctly snobby and condescending air about her, which stalled many a boy's advances. Even so, Seth himself had no desire to interact with her – she was leader of a clique of mean girls, and that imparted meanness onto her whether she was a bully or not.

Blake was trying for a free throw, and when she made it, Bailey jumped up and down and they hugged each other. That was a surprise, and Seth updated his Blake file: she made one free throw out of twenty he had seen this year.

The last truth, and the truth that Seth was both so anxious and so reluctant to learn, was that she had a crush on Seth Castle, and this truth was the most frightening to him.