“Immunology was so hard today.”
“Huh? I thought it was fine. The textbook explains the definition pretty clearly, doesn’t it?”
They were talking on a swaying city bus.
The bus crawled along the congested avenue in the south of the city. It was noon, school just let out, people were getting off work. The bus was packed, shoulders bumping. Some people stared at their phones, some just zoned out at the window. Most were students from nearby schools.
Two girls dressed like middle schoolers, brimming with that fresh teenage energy, had their heads together, chatting about the new topic they’d just learned.
“I get the definition—‘the body’s defensive response to foreign components.’ That part’s clear to me.” The short‑haired girl pushed up her glasses.
“Then what’s the problem?” The ponytailed girl nodded.
“But what counts as ‘foreign’?” The short‑haired girl frowned. “That definition isn’t really that clear, is it? Is it stuff that comes from outside? But food is from outside too, right?”
“Uh, I remember the teacher said some things inside the body also count as foreign components.”
“Really…” The short‑haired girl let out a troubled sigh. “These definitions are so complicated.”
“It’s not that bad.” Her friend tugged her hand, trying to comfort her. “Just remember that foreign components aren’t good things. That’s enough.”
“Uh… is that even right?”
“I think…”
“”
With the announcement, the doors slid open.
In an instant, it was like a floodgate bursting.
Footsteps rose up, the crowd surged. In the middle of that flood, a thin, small body with a backpack heavy as a snail shell was pushed toward the door whether she wanted it or not.
“Don’t block the way.”
“Move up.”
“Keep it moving.”
Everyone was looking forward, desperate to get off. No one looked at their feet. They all seemed to know exactly where they were going, and at the same time, seemed to have no idea at all.
The small hand gripping the pole was suddenly torn free. She tried hard to steady herself so she wouldn’t drop the heavy bag in her arms. But she couldn’t spare any attention for her footing. She stumbled, step after step, backward—carried by the flow.
“No, I’m not getting off…”
Her tiny protest was swallowed by the clamor of voices, just like her frail body was swallowed by the tide of people, until she was finally squeezed right off the bus.
The crowd that spilled out of the doors scattered in all directions, leaving only the little girl standing there in a daze.
“Don’t…”
Breathing a little fast, she bit her lip. She watched Route 40’s bus doors close and the bus pull away in a rush. She let out a discouraged sigh and slowly lowered the hand she hadn’t managed to stretch out in time.
She could catch the next one… It wasn’t that big a deal. It was just a shame… she hadn’t heard the end of it.
—So what exactly are “foreign components”?
Running through the rain toward the stop, the little girl realized in frustration she’d forgotten her umbrella.
She leaned against the ad board of the bus stop and set down the heavy duffel bag in her hands. Her right hand slipped into her pocket and pulled out the new phone Grandpa had given her before she left. She still wasn’t very good at using it. Her finger slid clumsily over the screen and, almost without thinking, she opened her contacts.
There were only a handful of names in it.
Her wandering gaze drifted over them, then her eyes and fingertip suddenly froze on one entry.
[Dabai]—two characters that carried a faint sense of warmth.
The little girl thought back to how that name had come about. Her lips pressed together, then the corners twitched up, just a little.
The man lifted his eyes slightly, deliberately provoking her.
The little girl glared at the exhausted man on the sofa, a cigarette between his fingers, and snapped,
The little girl bit her lip, then suddenly her eyes lit up.
The man cursed with a smile.
The little girl shook her head.
The man stood up and walked toward her. He raised his hand like he was going to smack her, threatening,
The little girl didn’t dodge at all. She stood her ground and met his gaze, stubborn to the core.
The man paused for a moment. In those clear eyes of hers, he read something unusual, something more than just childish pouting or joking around.
It was that serious, principled stubbornness that only children have.
He didn’t know what that “principle” was, or where it came from. But he respected it.
So the hand he’d raised slowly lowered—yeah, right.
Smack!
“Ow!” The little girl’s eyes flew wide as she grabbed her butt.
The man calmly withdrew his attacking right hand and chuckled. “There. Consider it a done deal.”
Before she could even get mad, the little girl froze and looked at him in confusion.
He smiled slightly. The tired curve of his lips held a gentle softness. “One smack in exchange for one form of address—that’s the Trade between the two of us.”
He blinked. “Just you and me—don’t tell a third person.”
“Just… you and me…”
Like she’d been struck by lightning, her pupils shrank to pinpoints at those words and trembled violently, as if they were about to melt away.
Not just her eyes—her thin, small body also started to shake. Her frail back seemed like it had always been bearing a mountain’s weight. She’d just been hiding it well. Only now did it ease, the door cracking open a sliver to let that suffocating pressure leak out.
But soon, the door shut tight again. The girl went back to how she always was. She lowered her head and bit her lip, her long hair hiding her eyes. With a trembling, muffled voice, she threw out her words like a curse.
…
…
Certain moments in the past always make you nostalgic.
But the little smile at the corner of her lips soon smoothed out again.
Staring at the name on the screen, her fingertip shook, but she never tapped it.
Her free left hand clenched slowly into a fist, showing the struggle inside her.
In the end, she still didn’t call. She slipped the phone back into her pocket.
“An agreement.”
Letting out a small breath, Shaohan quietly picked up her duffel bag and followed the crowd onto the bus, step by step.
“I’m definitely not going to be the first one to break it.”
…
…
