What makes a person tick?

How do people know the correct timing to smile, laugh, or yell?

Why do some people follow others blindly, while others shun people away?

Human nature was very complex, but Eren wanted to understand even the simplest emotions. He wanted to break through the outer shells of others to their raw core, to see their basic needs and desires.

He needed to understand others before he could control them.

When his fingers were hovering over the keyboard, he let out a dry laugh. What other choice did he have?

He put down human psychology for his major.

The cheers were deafening in his ears, but he tried to tune them out in favor of finding the quickest exit out. He scowled every time he had to pass through hugging friends and family members. There was no point in him saying goodbye to others, because he wouldn't miss anyone. He didn't understand how others could be so emotional over the words "good luck", "congratulations", or "goodbye!"

He spotted Mikasa and his parents out of the corner of his eye, and wanted to turn in the opposite direction to just wait at the car. It's not like he had any after graduation parties that he was invited to anyways.

"Eren!" Mikasa called out, waving him over. He tried not to glare as he turned around, putting a relaxed smile on his face instead. He didn't know why Mikasa tried to be friendly with him at times; it wasn't just because their parents were next to her either. He couldn't comprehend how she could reach out and be friendly to someone without any ulterior motives.

"Let's take a family picture together!" Carla laughed, handing the camera to a stranger. She beckoned Eren to come closer to Mikasa. Eren almost shrugged, not knowing why his mother finally put him in a family picture when he hasn't been in one for ages.

The bright light of the flash went off, and his head started hurting. With each flash around him, his smile dropped further and further into suppressed annoyance. But no one noticed, because no one ever paid attention to Eren Yeager.

His heart felt like exploding, and his lungs felt like they were bursting. He had a hard time taking another breathe, and he briefly wondered what would happen if he just stopped taking breaths.

He stopped running once he turned the corner and reached the curb of his house. He wiped away the sweat with his now looser t-shirt.

When he unlocked the door, he wasn't surprised to not see Mikasa or his parents. Mikasa was hanging out with her friends as often as possible before they all departed for college. Grisha was at the hospital working, while Carla was most likely buying groceries. His mother cooked more often now because she wanted to have Mikasa, and possibly Eren, enjoy home-cooked food before they left the nest.

He debated opening the freezer to feel the cool air against his face, but decided not to since he would be tempted by the ice cream stashed in there. He had been running about two or three miles a day, with a rest day in the week, ever since high school ended. He'd been dropping pounds, especially since he started watching his food intake. His lean muscle was starting to show again, but he wanted to build it up with weights. He didn't want to pay for a gym membership, so usually resorted to lifting heavy objects instead.

He went upstairs to shower, washing his newly cut hair. He had cut it the other week, getting long bangs that covered his forehead. His missed the comfort of his long hair, but from the pictures and magazines he had been studying he knew that long, skateboarder-length hair was out of fashion. He didn't mind not having hair stick to the back of his neck anymore though.

His parents had noticed some changes with him, but never bothered to question him about it. They were too busy trying to spend time with Mikasa, he scoffed.

He flashed a smile in the mirror, practicing the different angles of his lips. His braces from high school were taken off a little while ago. He remembered how he had to beg his parents for them back in middle school because his smile wasn't as perfect as Mikasa's. Now he had the pearly whites that he could show off.

Rubbing a towel into his hair, he walked into his room. He had cleared most of it out into boxes to take with him either to Trost or to the basement storage in their house. His parents wanted to turn his room into a guest room or entertainment room since he would be living in dorms. He had been a little annoyed by that, especially when he found out that they were keeping Mikasa's room as is, but later shrugged it off because he didn't really want to visit anyways.

He sat down on the bed, but immediately stood up when he heard the crinkling of paper. He put the notebook he had left on his bed onto his lap instead, and absent-mindedly flipped through the pages.

He wasn't as naturally gifted as Mikasa athletically or socially, and wasn't born smart like Armin. Eren was gifted with passion and dedication instead. When he was younger, before Mikasa had arrived, he had used that to his advantage to make friends and be popular. However, bitter jealousy over Mikasa curbed his passion into stubbornness and made him angry and sullen all the time. He had lost his dedication and had resorted to being in the background for his high school years.

This time, he felt his dedication spark up as he pushed himself to a new goal. It was already late August; 2 months after school had ended. He wanted to be ready for college starting in mid-September. He pushed himself to study all day. He was amused at his situation, because he had never had the will to study anything academic before.

However, what he was researching wasn't specifically academic. He researched everything that teenagers should know socially. From body language to popular bands, he wrote everything he deemed relevant into his notebook.

Before he didn't care about the different types of indie rock or different ways to wear skinny jeans, but now every little detail could be relevant to the people he would try to mold into his friends.

He tried not to stay up late researching, but was still tired from mental strain. As the words were swimming through his eyes as he read through magazine clippings and internet articles, he was bewildered at how much useless and yet useful information people his age kept in their minds. How did people remember information like this? But then, he supposed, these were things that probably interested them. Eren didn't have any personal interests, because he never felt the need to.

He had changed his working shifts to the maximum hours possible for him, as he wanted to save up as much money as possible. He now understood why teenagers spent so much money, at least compared to the old him before that never spent money to hang out. Why were people willing to spend hundreds on brand-name labels and useless gadgets? He had felt awestruck when he had looked up and calculated statistics for spending money and the amount that teenagers spent on weekly food.

He had spent the past week just researching various clothing websites and consulting different fashion blogs. He had browsed through hundreds of deals to calculate the best stores to go to. The week before that he had downloaded music and created playlists to fit different genres. He had playlists from grunge rock to foreign kpop that he could "share" interests in with others.

He was planning on going shopping at the mall tomorrow, but he really didn't want to not take advantage of all his free time. Plus, he didn't exactly feel like eating dinner with his family. Maybe he could eat dinner elsewhere and listen in to dinner conversations. He wanted to try out his research on popular teenager foods.

Mikasa had taken the car, but Eren supposed he could take the bus. He liked watching people interact on the bus anyways.

His shirts were all loose because he had dropped weight, so he had to deal with it until he bought new clothes. He put on a plain shirt and jeans, and made sure he had a couple hundred in his wallet. He caught the bus at around 5 so he would have time until 9 when the mall closed. The bus was half full of people coming home from work and half full of students going around places to enjoy the end of summer.

He sat in the middle of the bus, towards to the back. There were a couple businessmen around him and a group of high school aged girls giggling and chatting. The seat next to him was empty, and he liked it that way. When the bus went to the next stop, an elderly couple slowly got on. The bus was already full, with no more seats open. Eren looked around, noticing the change in body language. Some people had hastily avoided eye contact with them as they didn't really feel like getting up to give their seats away. He noticed some putting weight on their legs, with their hands on the seat to lift them up if needed. These people were debating whether or not to stand up, and their eyes darted towards others as if to say "I dare you to do it".

Curious, he stood up and motioned the elderly couple over. They came over with kind smiles and wordless "thank yous" on their lips. Eren felt positively beaming at that point-who knew that tiny actions like this would bring forth such undeserved praise. Was it really this easy to be "kind"? Did other people do actions like this and feel happy, or did they take praise for granted?

He leaned between the pole and the window of the bus, acting as casual as possible. He noticed out of the corner of his eye that the group of high school girls was giving him small look-overs every couple of minutes. They were either paying attention to him because of his appearance or because they thought he was more attractive because he was also kind, but the attention wasn't unwanted. How unusual he thought, as they chittered excitedly after he had flashed them a quick smile.

People were so interesting.

He had the mall memorized already, because he had spent so much time there alone during high school, so it didn't take him that long to get to the shops that he wanted. He had completely bypassed the old stores that he used to go to, since they were supposedly deemed "uncool", at least online. Cheapness was a factor that he had used before his change, but now he had to factor him trendiness and styles.

He wasn't shocked when he saw the prices, as he had already browsed online, but it still made him wonder why fashion was so important. He looked for the clothes he had wish-listed online, and let his gaze travel over to other teens his age that were buying clothes. He cataloged the types of clothes they put in their arms, and their comments when they passed by different racks. He had to put back a couple of shirts because some people had commented on how plain or tacky they were when they browsed through the racks.

He waited in line for the dressing room, humming along to the song playing on the store radio. It was song that was popular nowadays, and he was trying to memorize the lyrics.

He tried on a couple of shirts to gauge how loose he wanted them to be, and decided that he liked the ones that were tight enough to see the outline of his muscles, but not overly so. The jeans he chose were uncomfortable for him, but he decided that skinny jeans were probably the most popular choice, unfortunately.

"Nice shirt, do they have more of them in the front?" a random voice said, startling him. He had wandered over to the three folded mirror in the hall of the changing room to see his full outfit. He turned slowly, making sure to put an easy-going smile on his face.

"Yeah, they're on sale too. They're next to the jackets," he responded, received a nod from a boy around his age.

He made sure he put that shirt in his shopping basket.

"Do you need any help?" a pretty brunette asked, putting on a smile. He was a little surprised, because he never had anyone asking that whenever he had gone shopping during high school. Although, he supposed that his new look made him look more approachable.

He cleared his voice, working up a confident voice. He put on a hint of a smile that was between sheepish and kind. "Do you have any more of these shirts in the back? They don't have any mediums left."

She shook her head. "It's a sale item, so they were probably sold out earlier this week. We have more sale items in the back, if you'll follow me."

Eren followed the friendly employee and nodded occasionally as she pointed out the different shirts made by the same brand. He watched her behavior closely as she gestured wildly towards the various racks.

How does one know when someone is faking a smile? Was the sales clerk acting friendly because it was part of her job, or because she truly enjoyed helping out clueless people like him?

"Thank you," he said, adding his now perfected smile to the end.

He would need more practice.

Over the summer, Eren's notebook expanded. He quickly used up all the notebook pages, and instead decided to use loose sheets of paper so he could organize them based on topics.

He put his finishing touches on the paper he wrote on interactions between strangers that he observed on his way home from the park that he jogged around.

[Visual confirmation-checking for familiarity?

Stranger A, blonde girl, glanced at Stranger B, brunette boy, approximately 3 times. Similar age. Did not make eye contact. A's eyes typically lingered on B's face, while B looked at face and below shoulders. Stranger B did not look back after he left the bench, while A looked at B until he was out of eyesight. A had adjusted posture when B had entered eyesight.

A is self conscious/lonely, pushed chest out for better image? B had higher standards of beauty/body? A held more attraction to B than the other way around.

Research body posture in regards to males/females and male/female beauty standards. ]

Even the tiniest details that Eren observed throughout his day were recorded. Nothing was to be wasted; Eren could analyze details and find important information about humans.

He had started pinning some papers to his bedroom wall. It was easier for him to visualize and connect the different ideas he had that way. He also tied strings from thumbtack to thumbtack to establish connections.

Eren didn't have to worry about his parents coming into his room and panicking over the chaotic wall that he had. He was ignored during summer just the same as during the school year.

He hated it.

But he appreciated it as well. He had long closed off the part of his heart full of expectations for others. There was no point in having positive expectations of others, because no one ever lived up to them. It was a far better thing to underestimate people like the sorry creatures that humans were. In his eyes, he held his parents in a place between hatred and indifference.

"Did you finish packing up your room?" Carla asked unexpectedly one night at dinner. Mikasa wasn't at the dinner table because she was at the mall with her fellow club members.

Eren nodded, focusing most of his attention on his food. Why bother putting more energy into people who would not return it back?

"Well, uh, we've deposited some money into your personal account to help you with dorming," Grisha added, breaking the awkward silence.

Half of Eren wanted to ask, "Why bother giving me money now?" Getting a job in high school was both a curse and a blessing. His parents were glad that he was independent and not spending their money on trivial things, but they soon forgot about his monetary needs that normal parents would take care of. He often used his own money to pay for school supplies, field trips, and essentials. Mikasa, on the other hand, never got a job but his parents still freely gave her spending money.

"Thank you," Eren replied, not even bothering to fake his practiced thankful tone. "I've applied to some job close by campus already, but thanks anyways." He made sure he subdued some of his bitterness.

What did his parents actually think of him going off to college? They didn't display overt happiness over him not being a waste of space in the house, or fond sadness that their child was leaving the nest. Did the indifference he held for his parents transfer to them, making them feel apathetic to him as well?

No. He gripped his fork tighter, glancing furiously at his parents when they were too busy talking to one another to notice.

It was their fault that he felt this way towards them. They were the ones that ignored him first, and now he was just mirroring that sentiment. It was the lack of appreciation for their son that caused him to stop trying during high school. But now he would show them that they were wrong. They should have never paid more attention to Mikasa. They would regret it.

He would make them pay. He would make sure they regret every moment that they even thought of Mikasa over him. He'd come back from school full of achievements that'd make them ashamed of their previous treatment of him.

He felt relieved as soon as his parents drove off. They had driven him to Trost University so he could move into the dorm the weekend before school started. He lived in the on-campus dorming as was required for freshmen. Plus, he didn't have any friends in the same area that he could have dormed in an apartment with.

His goodbye to his parents was full of awkward hugs and his own half-promises of keeping in touch and visiting often. For all that he was concerned, he wouldn't even bother until he had built up his achievements so he could impress them. When he had gone with Mikasa the week before when she moved into the Sina dorms, he could notice all the tiny details that emphasized his parent's preference for her.

His father's eye corners were crinkled in the characteristic way that meant that he was trying not to shed tears. On the other hand, his mother had not held back the onslaught of tears that came forth. Her lingering hands on Mikasa's hair reminded Eren of how his mother always loved to comb through and stylize Mikasa's hair when she was younger. His father had offered some last minute advice that was sprinkled with reminders of the fond memories that they had together as a family, excluding Eren of course.

When his parents had said goodbye, every eye was dry. His parents had dismissed him in the manner similar to saying goodbye to the somewhat disliked neighbors on the corner of their street. But it didn't matter to Eren. What mattered now was the people he would meet that he would understand, control, and surround himself with for the next 4 years of college. Including the prick in front of him currently.

"I'm Jean Kirstein. I got assigned to your dorm but I already started moving into the dorm this morning. Do you mind if I take the bottom bunk?"

From Eren's research, first impressions were high on the importance list. While they don't make or break a person, they always leave a lasting image that are the basis of comparisons. Already, he could tell that his previous self would not like Jean one bit. He could already tell that he was self-absorbed, rich, and keen on talking about himself. His overly groomed appearance, brand name shirt and jeans, and way of not waiting for Eren to introduce himself already stirred Eren's fighting spirit.

But this was a perfect opportunity for him to show himself how much he changed. He was completely different from the Eren from childhood and high school, the one who lived in the shadow of Armin and Mikasa. This Eren was unattached, free, and open-minded. If Jean was to be his dorm-mate, Eren needed to make sure they would get along, even if Eren had to completely resist the urge to punch him sometimes.

He plastered on the same smile that he practiced in front of the mirror. "I'm Eren, and sure, I don't really mind."

Lie. He hated top bunks. But Eren found himself building up his character that he envisioned in his mind during summer; someone who was not a complete pushover, but still open-minded and caring. Lies after lies spouted off easily from his tongue.

"At least I won't have to worry about terrible roommates, huh?" Eren joked, letting an easygoing smile appear on his face. Jean agreed, laughing obnoxiously. "I'll show you around to some of my buddies here, since you're not from this area."

"Thanks, man. Dinnertime's pretty close."

Everything was perfect so far.

AN: I spent a longer time on this chapter, compared to the first chapter where I busted it out in one full day. This took me at least two weeks to write all the parts and another to just edit it how I wanted it. So, sorry for the delay! I was having a hard time imagining Eren's thought process. I wanted to make his logic concerning the relationships between his parents, Mikasa, and him more clear.

Next chapter should come out in 2-3 weeks. Please leave any reviews and suggestions!