The Yao Class experts stepped in to clarify. The number was in binary — it represented nineteen.

Zhang Yuge inserted a single gold candle into the top of the cake. “Come on — let our birthday boy make a wish.”

Xie Yichen took the stiff paper ring included in the packaging, fashioned it into a little hat, and set it casually on his head. As the candle was lit and beautiful sparks bloomed, he sat down before the cake with both hands clasped.

Lin Shuyu started singing “Happy Birthday,” and before long, Xie Yichen opened his eyes and lifted a corner of his mouth: “Wish is made.”

Party poppers burst open, and confetti scattered all over the ground.

“Happy birthday to our A’Chen!!”

“Thank you all.” Xie Yichen removed the little hat from his head. His expression was gently bright. “Today has been a really good day.”

He so rarely said things like that. Zhang Yuge was immediately energized — didn’t that mean his own efforts organizing tonight had paid off? All that running around had absolutely been worth it.

People started dividing up the cake. Lin Shuyu cut with the knife and handed the first slice to Xie Yichen, and the second slice — reaching past several of the guys at considerable distance — to Ning Sui. Zhang Yuge, in particularly unfiltered form, settled into the seat beside Xie Yichen and clinked his glass against his: “You’re welcome.”

Their closeness was plain to see. Hu Ke’er leaned in curiously: “Wait — I’ve always wondered, how did you two actually meet?”

Zhang Yuge lounged back. “Did we not tell you back in Yunnan?”

“No,” Hu Ke’er said. “You only told us about the time you wet yourself as a kid and your mom beat you for it.”

Zhang Yuge: “……”

Lin Shuyu raised his hand and piped up: “I know, I know — they met in a fight.”

“A fight?”

Nobody knew this. Everyone leaned in around their cake slices, and Lin Shuyu snorted: “Apparently young Brother Fish was way too annoying in middle school.”

Zhang Yuge: “……”

Back in those days, he and Xie Yichen had shared a strange, accidental kind of chemistry.

Zhang Yuge genuinely didn’t understand how it happened — he’d known the guy had a sharp temper, and yet he kept finding himself gravitating toward him, grinning that brazen grin of his. Xie Yichen had eventually asked flatly whether he wanted to fight.

Zhang Yuge, young and reckless, thought: who does this guy think he is?

There was something defiant in him. The more he was pushed away, the more he wanted to catch Xie Yichen’s attention — make him look at him just a little longer. So he’d pointed at his own face and said: “Go on, hit me here if you want.”

Having issued that kind of invitation — it would practically be disrespecting the person not to follow through.

So that evening, they both went home looking a little worse for wear.

The next day, Zhang Yuge had some kind of lapse in judgment, bought Xie Yichen a tube of medicinal ointment, and left it in his desk drawer. Xie Yichen apparently never used it.

How had they gradually gotten close after that?

Oh. He thought he remembered. There had been a time when Zhang Yuge bombed a math exam — fifty-something points — and his tiger mom had torn into him and forbidden him from playing any games for two months and confiscated his allowance.

In a rage, he’d sworn he was going to run away from home, though in practice he could only bring himself to go sit sulking at the entrance of the apartment complex.

Across the street, an elderly man was selling candied hawthorn skewers. A father and young child passed by; the child fussed and asked for one, and the kind father bought it without hesitation. Zhang Yuge was struck, all at once, with a profound sense of injustice. How was it fair that some kid could have a hawthorn skewer, when his own backside had been beaten to look like two hawthorn-shaped lumps, and his dad wasn’t even here?

The pain was still fresh every time he shifted. Math was brutally hard. Zhang Yuge didn’t know what came over him, but his composure crumbled, and he just started crying.

Xie Yichen was renting a place not far from Zhang Yuge’s family at the time, and happened to be passing by on his way home from school. He looked up, and their eyes met. Zhang Yuge figured bawling in public was genuinely embarrassing for someone his age, so he quickly started wiping his face — but the more he wiped, the worse it got, snot and tears everywhere, a total disaster.

He’d assumed Xie Yichen would ignore him. Instead, the guy went across the street, bought two candied hawthorn skewers, and came to sit beside him.

“I remember your Chinese is pretty good,” he said, completely matter-of-fact. “My essay went off-topic. How do you always score so high?”

Zhang Yuge was completely caught off guard and could only say, vaguely: “Your math is pretty good too.”

A skewer was held out toward him. Then he heard Xie Yichen say, cold and unhurried: “Yeah. Let’s be friends, then.”

It was probably that offhand compliment from Xie Yichen that planted the idea in Zhang Yuge’s head — that he had genuine talent in Chinese. That confidence stayed with him, and by high school, his essays were regularly read aloud by teachers as model pieces.

Zhang Yuge didn’t understand until much later that underneath all that ice, Xie Yichen was someone who felt things deeply — someone with warmth, who protected the people he cared about, who drew clear lines between what mattered and what didn’t on his personal compass. Once he’d decided on someone, he just kept being good to them, without reservation.

Being his friend felt solid. You never had to wonder if today he was your friend and tomorrow he’d moved on to someone else. Zhang Yuge had always believed that in Xie Yichen’s eyes, he held a particular place.

Over all these years, he felt genuinely lucky — to have stayed at his friend’s side without falling behind.

As Zhang Yuge finished the story, something suddenly crystallized in his mind and he leaned over with a grin, the smell of alcohol on his breath: “You know what — I’m basically the one who broke through the ice, right? It was me. From the very beginning. My selfless love and acceptance thawed your cold, iron heart.”

Xie Yichen didn’t bother: “Get lost.”

He raised an eyebrow: “You owe it mostly to your own foolishness — for showing me how varied the world is.”

Whatever, whatever. That counts, that definitely counts.

Zhang Yuge, newly enlightened and delighted, let his spirits lift.

The wilder memories of youth — best left where they were.

He bustled over to bring the milk tea tote bag closer and called out warmly: “I ordered this place’s new tea.”

Before anyone had realized it, they’d been talking for quite a while. Everyone gathered around cheerfully. Zhang Yuge set each cup out on the table. “Just grab your own.”

Xie Yichen, head lowered, methodically read the label on each cup. Lin Shuyu was being picky: “They all taste the same, don’t they.”

Zhang Yuge: “Stop picking. You’re lucky to have one at all.”

Lin Shuyu was all smiles: “Right, right. Brother Fish, you’re too generous.”

Zhang Yuge shot him a look: “Say that again and I’m done with you.”

Ning Sui went over to look, blinked, and quietly went back to her seat.

They were all some variation of glutinous rice and taro bubble tea — she was dying for one, but she was allergic.

It wasn’t a severe allergy, nothing too dramatic. As a child, whenever she’d given into temptation and snuck bites of taro desserts, her face would turn quite red and she’d feel itchy all over her body — but after a few hours, it would pass on its own.

Ning Sui had even, at the risk of being severely scolded by Fangfang, conducted a few secret experiments: she’d figured out that foods adjacent to taro, like the grass jelly in mixed-ingredient chilled desserts, were fine for her — it was just eating the taro balls directly that caused a reaction.

She glanced at the time. Somehow it was already past ten.

Ning Sui had just finished replying to a message in the family group chat, head bowed, when she felt someone settle beside her.

Xie Yichen was holding a cup of milk tea. He looked at her and said in an unhurried tone: “Want some?”

Ning Sui: “I’d love some, but there are taro balls in it.”

In the glow of the candlelight, her eyes were especially beautiful — lashes long and curled, the irises clear as some kind of translucent jade.

“Drink this one.” Xie Yichen set the cup in his own hand down and pushed it toward her without preamble. “I already asked the restaurant for a bamboo skewer and fished them all out — you won’t have a reaction.”

Her breath caught. Ning Sui fixed her gaze on this steaming cup of milk tea, and for a moment, said nothing.

Her heart skipped a beat, then resumed — and inside her chest, it felt like a great many bubbles were churning and rising, each one clearer and more distinct than the last.

Ning Sui’s lashes trembled faintly. She tried to suppress the rush of feeling that was growing more insistent by the second.

— He’d said: if he liked someone, he would treat that person very, very well.

But in Ning Sui’s observation, he was good to all of his friends.

Zhang Yuge went without saying — they’d just heard the story. Lin Shuyu was much the same — on his birthday, he’d even received a steak that Xie Yichen had cooked himself. Qu Handong and Liu Chang had mentioned that Xie Yichen often saved spots for them, and never minded taking on more than his share of group project work. And even the second-year upperclassman here tonight — though Xie Yichen didn’t know him very well — he’d been thoughtful enough to invite him, figuring the guy would want someone to celebrate with after the competition.

And just now — when the sparks from the candle burst out, he’d instinctively reached out to shield Hu Ke’er from being spattered.

Ning Sui made a soft sound of acknowledgment, pressed the straw down into the paper cup, lowered her head, and took a slow sip. Then, after a pause, she said unhurriedly: “So — did you always write off-topic in your essays when you were little?”

“……”

Xie Yichen’s jaw tightened slightly. His expression suggested he wasn’t quite sure whether he’d been made to laugh or was faintly exasperated. He looked straight at her, tugged the corner of his mouth: “……Just that once. And the college entrance exam.”

Ning Sui: “Zhang Yuge said your narrative essay scores were never as high as his.”

“Don’t listen to Zhang Yuge’s nonsense.” Xie Yichen said with resignation. “……I was trying to make him feel better.”

“Oh — so you’re actually quite good at comforting people.”

Ning Sui lowered her head, found a strand of hair caught in her down jacket zipper and worked it free. She took another small sip of milk tea and tucked her warm ears further into the folds of her scarf. “So — back in second year of high school, when you told me you’d also found that problem hard at first — was that a lie too?”

Xie Yichen went still. His gaze deepened.

This was the first time she’d brought up the academic competition training from their second year of high school in front of him.

“It was genuinely hard.” Their chairs were close enough that they could hear each other breathe. Xie Yichen had drunk a fair amount tonight — his breath was faintly warm. He watched the soft, gentle line of her profile where it was half-hidden by the scarf, then let his gaze drift, the curve of his lips gentle: “I’m not a god. I’d missed a few days of class — managing to catch up on the material at all was the achievement.”

“Mm.”

Ning Sui nodded, and let the topic rest.

Neither of them spoke for a while. The moon hung high and poured down silver light. She suddenly thought this felt very much like that last night at the training — the two of them sitting side by side on the staircase.

How peaceful.

When they’d first run into each other again in Yunnan, she’d thought he’d forgotten her entirely.

“Xie Yichen.”

“Mm?”

“Happy birthday,” Ning Sui said softly.

The outdoor patio was slowly emptying as diners at other tables trickled away. Lin Shuyu was drinking on his own beside them and suddenly propped himself upright, sniffing the air: “How come I smell roast duck? It smells so good.”

“Where? You’ve had too much to drink,” Zhang Yuge murmured from where he was slumped against Lin Shuyu’s chair back. “You still have room?”

Lin Shuyu: “No, it just made me think of the old days — sneaking out of school at night to get food. Those were good times.”

They really were good times. Skipping class to play basketball, racing downstairs to grab food before it ran out, throwing yourselves with full confidence into every speech competition and academic meet, cramming in a frantic last-minute review the night before exams, the walls of the bathroom covered in scrawled vocabulary and formulas.

Everyone pushing in the same direction, making noise and making trouble, but walking together all the same.

Such beautiful days.

Zhang Yuge said: “Now is also good.”

Lin Shuyu thought about it. Best friends nearby, gathered around a fire brazier on a cold winter’s night, stealing time away from the busy pace — yes. It really was good.

Hu Ke’er, a little flushed from drinking, inserted: “Do you all know about the Proust Effect?”

Zhang Yuge: “No — what is that?”

“It’s when you smell something from the past and it triggers a memory associated with it,” Hu Ke’er said. This seemed like the right explanation for what had just happened with Lin Shuyu.

Zhang Yuge had an epiphany: “That’s why every time I use the bathroom at our old high school, I think of Kuge vividly eating pizza.”

Lin Shuyu: “……”

It was getting close to time to wrap up. Everyone had things to do the next day, so no one suggested moving on to another venue.

Qu Handong’s group and the upperclassman called a car to go back together. Xie Yichen and Lin Shuyu’s side called a six-seat commercial vehicle — in order along the route, they’d drop Zhang Yuge at his school first, then deliver the two girls to Jingda.

Lin Shuyu was the type who was terrible at drinking yet couldn’t stop himself, and his gait was less steady than Hu Ke’er’s right now. Xie Yichen gave the driver a little extra money and asked him to wait a moment at the curb, then pulled on his jacket, got out, and walked over to Ning Sui.

Ning Sui, watching him look at Hu Ke’er — who was swaying noticeably — carefully moved to support her arm, then looked up with some effort to say: “I can hold her steady.”

Hu Ke’er, draped like soft clay against Ning Sui’s shoulder and apparently with some ancestral DNA activating: “Who said I was fat?!”

“……”

Xie Yichen’s gaze settled on Ning Sui. “I’ll walk you both to the dorm entrance.”

The palm of Ning Sui’s hand tightened: “Okay.”

The air had grown noticeably colder. She felt her ears losing sensation in the cold, yet somehow they were also quietly, inexplicably warm.

Xie Yichen and Lin Shuyu each took one side, flanking the two girls between them. It was nearly midnight, but the campus paths were still full of students moving quickly from place to place. Xie Yichen kept an eye on the two slightly unsteady companions beside him while walking at an unhurried pace.

After a moment, he said quietly: “So — you got me a scarf?”

Ning Sui’s step faltered: “You already looked?”

In the car earlier, Xie Yichen had opened the pink packaging box and taken a peek — inside was a light caramel-colored wool scarf, which was notable in that it was covered from end to end in mathematical formulas. Among them, the Katz–Tao inequality they’d once discussed together had been placed right in the center, in a prominent position.

His throat moved. He looked at her: “——You didn’t actually make this yourself, did you?”

Ning Sui’s heart skipped.

“As if I could make something this nice.” She looked down at the path ahead. After a brief pause, she said in a calm, honest voice: “I bought it online.”

Xie Yichen paused: “Mm.”

The girls’ dormitory was not far from the gate they’d come in through — less than ten minutes, and they were there. Xie Yichen caught Lin Shuyu before he could follow them inside, then said: “Get back safe. Rest early.”

Ning Sui: “Mm. Good night.”

After quite a long while, Lin Shuyu still hadn’t noticed any movement from the person beside him. He blinked his hazy eyes and looked around — the two girls were already gone. He ambled close to Xie Yichen and announced generously: “Bro, you’re really warm to lean against.”

Only then did Xie Yichen seem to come back to himself. He shot Lin Shuyu a sideways look, then hauled him by his collar with no particular gentleness: “Do you think you could have a slightly more accurate picture of your own alcohol tolerance?”

Drunk Lin Shuyu was very full of himself: “What? I’m not the one who drank you under the table?”

“……” Xie Yichen’s grip didn’t loosen one bit. “Still conscious?”

“Wide awake. Light as a feather.”

“……”

“Got something to tell you.”

“Go on. Why so formal? Finally figured out I’m your dad?”

What the —

The uneven asphalt surface was dotted with texture underfoot. Xie Yichen’s lips curved with an expression that was difficult to name — something between a real smile and something that wasn’t.

After a moment, he spoke: “Seriously. If you’re not in the right headspace tonight, we can talk another time.”

The night wind hit, and Lin Shuyu became a fraction more alert. He responded carelessly: “What is it?”

“Do you still have feelings for Ning Sui?”

Lin Shuyu went completely blank.

The streetlamps burned above them, casting long, thin shadows. The old architecture of the main auditorium stood at their side — grand and full of a quiet dignity.

Xie Yichen looked at the lamp beside them, the line of his jaw sharp and clean in the light. “I’ve never mentioned it to you or Zhang Yuge — but Ning Sui and I actually got to know each other during the academic competition training in our second year of high school.”

Lin Shuyu was bewildered: “What?”

“I’m sorry — the full reason will have to wait until she’s comfortable sharing it. But — I did know her first.”

Lin Shuyu thought back to the Truth or Dare game in Yunnan — the one Zou Xiao had proposed, where Ning Sui had to have a shared toast with the person she’d known longest. He felt as though he might be starting to understand — or perhaps not quite.

“So — and then what?”

Xie Yichen said: “You told me before that you weren’t going to pursue her anymore.”

The alcohol was muddling everything. Lin Shuyu let out a rough breath, stared at him for a long moment, and asked, brow furrowed: “A’Chen, what exactly are you trying to say?”

They were face to face. Xie Yichen raised his eyes without flinching, and let out a quiet, sudden laugh. “So no matter what I do — I’m not taking something that was someone else’s, right?”

“……”

Lin Shuyu opened his mouth. He started to say something, then couldn’t. He watched as Xie Yichen looked directly at him, those dark, striking eyes steady and unyielding: “If you haven’t given up — I won’t yield either.”

He paused, then held his gaze without wavering: “And if you genuinely mind — you can hit me once.”