Lin Shuyu took a good while to fully process what Xie Yichen had said.

They’d known each other since second year of high school. So all this time, he’d been hiding it. Even in Yunnan, the act had been convincing.

Whatever the reason he couldn’t say — did this person even see them as brothers?!

Whether it was the cold wind hitting too hard or the alcohol going to his head, Lin Shuyu felt his chest pounding with heat, rising and falling. And then he really did throw a punch at Xie Yichen.

The force behind it was no small thing. Xie Yichen had drunk quite a bit himself that night and had no particular interest in absorbing the full impact — he involuntarily stepped back half a pace.

The pain bloomed and spread immediately. He knew this feeling well.

Lin Shuyu looked up in a daze, suddenly registered the clearly visible wound, and felt the sting in his own knuckles. “Holy — I didn’t mean to hit that hard.”

Xie Yichen pressed his brow together and raised a hand to touch the corner of his mouth.

He tasted copper — the skin had broken and bled. Something low moved through his throat in a faint huff of breath.

He hadn’t reacted much yet, but Lin Shuyu was already feeling the guilt.

It was hard to say who was really in the wrong here. His friend had known this girl for so long, and had probably been serious about her this entire time — all while holding back out of consideration for Lin Shuyu. And Lin Shuyu himself? He’d said he was done pursuing her, and yet he’d kept, out of sheer habit, finding reasons to do things for her.

Thinking about it that way — he was pretty terrible about it too.

Lin Shuyu straightened up with grand magnanimity: “You should hit me back. One for one.”

He shouldn’t have said that. Xie Yichen had been quietly fed up ever since Lin Shuyu had so eagerly handed Ning Sui that piece of cake, and his jaw locked slightly. He raised a fist — and then felt the laugh rising before he could stop it.

“What are you dodging for.”

Lin Shuyu let out a dry cough: “Reflex.”

“……”

They settled things one punch each and sat on the edge of a nearly empty sports field to apply some ointment.

Lin Shuyu was cautious and fussy about it — hissing at every dab, delicate as anything. Xie Yichen did a simple disinfection, slapped on a bandage strip at an angle, and looked thoroughly unbothered.

He hadn’t thought about how it might look until he pulled out his phone and used the screen as a mirror. Then came a low sound from his nose.

Lin Shuyu, sitting beside him, involuntarily shuddered. Only then did it occur to him — today was still this person’s birthday — and he raised his hand again in solemn restatement: “No, really — bro, I genuinely didn’t mean for it to be that hard.”

“……”

What Xie Yichen was actually thinking about wasn’t that at all.

He was thinking: knowing Ning Sui and her perceptive nature — if she saw this before it healed, she’d be all over him with questions about what had happened.

He could make something up to brush it off. But he didn’t want to lie to her.

So however long this wound took to heal — that was how long he’d have to go without seeing her.

……Annoying.

Xie Yichen let out a quiet “tch,” leaned back on both hands against the stone ledge, sprawled his legs open, and looked up at the particularly bright, brilliant moon.

Lin Shuyu was still worrying when the person beside him suddenly burst out laughing — easy and free: “It’s been a while since I’ve gotten into a fight.”

Lin Shuyu honestly: “Yeah.”

That’s why the force was off.

He paused, then said something characteristically absurd: “I only ever use reason to win arguments.”

Xie Yichen curved his lips: “Get lost.”

Lin Shuyu was actually deeply curious about everything to do with Ning Sui, but since Xie Yichen had said it wasn’t his to tell, he swallowed all his questions. Including quite a few others.

The two of them sat together there. Lin Shuyu also looked up at the moon, and after a while said: “I’m actually really happy tonight.”

Xie Yichen looked sideways at him: “How so?”

“I used to be so jealous that Zhang Yuge got punched by you — that’s why you two are closer.” Lin Shuyu said with genuine cheer: “Now I’m in the same club as him.”

He’d always felt there was a layer of gauze between himself and Xie Yichen — more distance than between Xie Yichen and Zhang Yuge. Now that was solved. He felt he’d been punched into the inner circle.

“……”

Xie Yichen: “You two are both genuinely unwell.”

—

Mid-December was a fairly hectic time. Ning Sui had let some of her coursework slide for musical theater rehearsals — only keeping up with the assignments, without giving those classes much deeper attention. Now she began catching up, and the library became her regular territory. Whenever she had free time, she’d head over and sit for hours.

Her dorm was in much the same state as before. Liang Xinyue was studying at half-effort; her childhood sweetheart had come to visit, giving her a brief respite from long-distance. Bi Jiaxi wasn’t in any clubs, so it was classroom, dorm, and dining hall in a steady rotation — she and Ning Sui ran into each other at the library sometimes.

Yu Qin was probably having the hardest time. Her midterms hadn’t gone well, and she’d been in low spirits. One night Ning Sui got up to use the bathroom and found her awake, head down on her desk, quietly crying.

Ning Sui pretended not to notice. After that, she and Liang Xinyue and Bi Jiaxi took turns bringing late-night snacks to the room and spending time with everyone — they watched comedies and stand-up specials together to decompress.

Because Ning Sui spent so much time at the library, she inevitably ran into familiar faces. Yin Rui showed up to study sometimes too; noticing she was working through advanced algebra problems, he’d smile and exchange a few words.

Their acquaintance warmed slightly. Yin Rui offered to save her a seat so they could study together next time. Ning Sui declined politely, and he didn’t push. They still crossed paths occasionally, though — after a while, Ning Sui started bringing Hu Ke’er along to keep her company.

One evening back in the dorm, Yu Qin was curled up in her chair watching a drama, looking cheerful. Liang Xinyue had just ended a call and was clearly in a mood — she explained: she’d planned to ring in the New Year with her boyfriend, but his family had something come up and he needed to go home for the break. He’d offered to have her come along, since both families knew each other well.

Liang Xinyue wanted to be with him, but that would upend all their original plans. She pouted unhappily: “I even bought tickets to the Strawberry Music Festival — they were so hard to get, and now they’re wasted. What a pain! That terrible man!”

After ordering fried chicken, she calmed down slightly and asked the room: “Does anyone else want them? I’ve got no use for them now.”

Yu Qin cradled her face in her hands and let out a mournful sound: “I don’t have anyone to go with.”

Bi Jiaxi raised her hand: “Same.”

Everyone’s gaze fell on Ning Sui. She pressed her lips together lightly, kept her voice level: “Then give them to me.”

“Ooh, ooh, ooh.” Liang Xinyue immediately scented something. “There’s a development.”

“There isn’t.” Ning Sui sat up straight, genuinely thought for a moment, and said: “I’ve just never been before. I want to see whether eating a strawberry while at the Strawberry Music Festival makes it taste better.”

“……”

However much they teased her, she maintained her composed expression. Liang Xinyue sent over the ticket screenshot, Ning Sui saved it to her photo album, and that evening at nine, lying in bed, she opened up Xie Yichen’s chat window.

They hadn’t talked in a few days. She retraced their last exchange, thought through how to phrase it, and typed simply: 【That Artificial Intelligence assignment — I think I’m still a bit stuck.】

And at the same moment — the other side also sent a message: 【That AI coursework you mentioned — is there anything I can help with?】

Ning Sui stared at the screen, her lashes giving a tiny faint shiver.

The next message came: 【Is it urgent?】

Oreo: 【If it’s urgent, you can send the files — I’ll take a look.】

Suisuisui: 【Not too urgent — about two weeks, I think.】

She paused, then typed slowly: 【It’s a little complicated to explain.】

Suisuisui: 【Might be easier to talk through in person.】

Ning Sui had just sent the compressed file over and was about to ask if he had time to study together — when Xie Yichen sent her a screenshot.

It was his course schedule.

But not just course listings — this was a full daily planner, showing not only his classes but also what he planned to do in each time block, clearly organized. Ning Sui scanned it at a glance and caught words like “Shanying,” “Robotics,” and “ACM Finals Preparation.”

It felt as though, just like that, his life was being laid open in front of her — calmly, naturally, without any fuss.

Oreo: 【Any of the open slots work for me.】

His tone was unhurried: 【Whatever time you’d like is fine.】

Ning Sui lay curled in her blanket, those peach-blossom eyes of hers looking at those two messages with a steady gaze, though the light from the screen had made her eyes more luminous than she herself realized: 【Would Friday afternoon work?】

On Friday, he seemed to be free until eight in the evening — and the musical theater rehearsal also started at eight. She wondered, vaguely, whether they could have dinner together beforehand.

Oreo: 【Yes.】

Oreo: 【Jingda or Qinghua? I can come to you, or come pick you up — either works.】

Pick her up?

Something brushed lightly across the tip of Ning Sui’s heart: 【Qinghua is fine — I’ve never been.】

Oreo: 【Alright.】

When Friday came, Liang Xinyue woke up at half past one in the afternoon and came out to find Ning Sui already packed and ready to head out. Her eyes lit up: “You’re looking especially nice today — don’t tell me you’ve got a date?”

She’d only meant it casually. Ning Sui’s step faltered by half a beat. She kept her eyes wide and straight-faced: “I’m off to audition for a storefront window model.”

“……”

Downstairs, she found Xie Yichen already waiting at the entrance to her dormitory building. His motorbike was parked beside him. He was in a casual look — a thick bomber jacket over a dark hoodie, paired with light gray athletic joggers that made his legs look impossibly long — and had a backpack slung over one shoulder.

Ning Sui noticed he was wearing the caramel-colored scarf she’d given him. The combination worked well.

Foot traffic flowed around them. A few girls quietly directed their gazes toward him, but he seemed completely unaware, relaxed and comfortable, head lowered, scrolling on his phone.

Ning Sui shuffled over in small steps. Before she’d even reached him, Xie Yichen looked up, and those dark eyes found her at once, settling there.

He straightened up. Ning Sui tugged at her backpack strap, and her gaze, still brightened by something faint, fell on the mathematical formulas stitched into the scarf.

Maybe it was Liang Xinyue’s comment still lingering — this clearly wasn’t a date, but somehow, look at it as she might, it had a slightly date-like feeling.

Ning Sui’s lashes moved. She tipped her head back to ask: “Did you wait long?”

She was right on time. Xie Yichen lowered his gaze — fortunately he’d come twenty minutes early — and smiled softly: “No, just got here a little while ago.”

She nodded.

Xie Yichen secured the bike’s kickstand, tucked his bag at his feet, and started the engine with steady ease: “Get on.”

This wasn’t her first time on a bike with him — familiarity had long since replaced hesitation. She put on her helmet and got ready.

Just as she settled in, she heard him say quietly: “The skirt looks nice today.”

She hadn’t expected him to say that.

Ning Sui went still for a moment, then said faintly: “Oh.”

The motorbike moved forward along the wide road. Ning Sui watched Xie Yichen’s broad back, and felt something soft stirring in her chest, though she couldn’t quite name it.

Normally she was quite averse to physical contact with other people. But right now, somehow, it didn’t seem to matter.

After all — they’d hugged before. At this point, what did it matter?

With that thought, Ning Sui carefully lifted both hands and, tentatively, lightly gripped the sides of his jacket hem.

The spot she landed on was somewhere forward of his side waistline — which meant it looked, to any observer, as though she was loosely encircling his waist. Xie Yichen, without drawing any attention to it, glanced down at the corner of his eye — and saw her slender fingers, pressed pale into the fabric. The corner of his mouth lifted, quiet.

Ning Sui hadn’t noticed. She was looking sideways at the scenery rushing past.

She genuinely loved seeing the world from this vantage — like moving through something unexplored, everything new and fleeting. Fangfang had restricted so many things throughout her life, so even something as simple as riding on a motorbike carried a peculiar freshness.

The bike exited the Jingda campus gate and merged into the road.

Beyond the rumble of the surrounding cars, the space between them felt strangely, almost excessively quiet. Ning Sui buried her nose in her collar and reached for something to fill it. “You wore the scarf.”

He made a sound of acknowledgment.

“Is it warm?”

“Mm.”

The wind was loud. Xie Yichen gave a lazy, low laugh: “Come a bit closer — I can’t hear what you’re saying.”

Ning Sui looked down and silently assessed the already-minimal gap between them on the seat.

“It’s already pretty close.”

Xie Yichen said, with complete composure: “Not enough. We’re going pretty fast — I’m worried you’ll fall off.”

Ning Sui: “I won’t fall —”

She hadn’t finished the sentence when the bike came to a sharp stop. She pitched forward automatically, and her cheek pressed tight against his back. Both hands reflexively tightened, and she found herself holding firmly around his waist.

Which made it a real embrace.

Even through her thick down jacket, her heartbeat was racing. The tips of her ears had gone red — half from the cold, half from something else. The cars around them had all stopped obediently at the light. Mortified, Ning Sui called out: “Xie Yichen!”

From the front came a low, quiet laugh. He raised one finger and pointed above: “Red light.”

“……”

In the end, they chose the North Library at Qinghua. The environment there was pleasant — the tables and chairs spacious and clean. When they walked through the entrance, the common area on that floor was almost entirely full. Their arrival seemed to attract a fair bit of quiet attention in the corridors.

Xie Yichen had booked a private seminar room — soundproofed for discussion, fully enclosed, so no one could see in or out. No interruptions.

As soon as she was in an academic environment, Ning Sui shifted into focus mode. She opened her laptop and pulled up the development software.

The assignment was a simulation of gravity-based Connect Four. Xie Yichen had glanced at it beforehand and figured it would probably take him a day or two to complete: “Have you started writing it?”

Ning Sui answered plainly: “A little. The board evaluation section isn’t working yet — I don’t really have any experience with Connect Four, so I’m not sure how to assess the state of the board.”

Xie Yichen: “You’re using the alpha-beta pruning algorithm?”

Ning Sui: “Yes.”

He nodded, then browsed through her code as he spoke: “That approach relies heavily on the position evaluation function, and the function itself is really hard to construct.”

He thought for a moment. “How about you use Monte Carlo Tree Search instead — it doesn’t require evaluating the board state directly. The idea is mostly based on running simulations: simulate the game repeatedly and record the win-loss statistics. AlphaGo works on a similar principle.”

Ning Sui thought he knew so much, and asked with genuine curiosity: “That artificial intelligence that plays Go?”

“Right.”

When Xie Yichen was concentrated, his expression went cool and sharp — his jawline strong, his profile clean, his lashes distinct and precise. Ning Sui propped her chin on her hand and looked at him sideways, quietly, and felt something inside her give a soft, gentle tug. Her lips curved almost without her choosing.

He seemed to sense it. He glanced sideways, his expression hovering between amusement and something else: “What are you looking at?”

Ning Sui snapped her gaze back to the screen and stared at the code without blinking. She pivoted with great determination: “So — let me draft out a framework first.”

“……”

For the next several hours, both of them kept largely quiet. The occasional tapping of keys broke the silence. Every so often they exchanged a few lines — always Ning Sui posing a question, Xie Yichen explaining it with clear logic: how to implement the Upper Confidence Bound for Trees in the Monte Carlo method, how to improve the efficiency of the simulation code.

Something Ning Sui hadn’t noticed before: there was actually a strange resonance between computer science and mathematics — and also a perfect inversion.

One used simple language to describe a complex world. The other used complex reasoning to keep reinforcing the simple foundations of that world.

When she’d finished a section, she pushed the laptop toward Xie Yichen to ask: “Is this what you meant?”

He read it, then said: “Yes.”

His brows lifted slightly: “You actually have quite a talent for this.”

Ning Sui’s fingers curled in surprise: “Really?”

She paused: “Maybe because you explain things well.”

“No.” Xie Yichen looked at her steadily. “I’m just a guide. The real understanding is yours — you pick things up very quickly.”

Ning Sui was quiet for a moment.

Fangfang had never really said things like this — never told her she had a gift, or that she was brilliant.

Because Ning Sui always scored well, nothing she achieved surprised Fangfang anymore. High standards and high expectations had become the default, the unspoken floor. And her father, Ning Deyan, typically deferred to her mother on these things, or simply didn’t think to express a view. So the only thing Ning Sui had ever heard was the next challenge, the next push forward.

She rubbed the pad of her finger softly, and gave a quiet sound of acknowledgment.

After that, Ning Sui poured herself back into the code, and — whether it was the praise or something else — felt a surge of motivation. She looked up at the clock on the wall without thinking, and nearly startled: it was already five-thirty.

The takeout they’d ordered had also just arrived. Xie Yichen brought the containers inside.

She decided to take a break and check her phone.

She caught sight of Xie Yichen, in her peripheral vision, idly tugging at a loose black thread running along the edge of the mathematical formulas on the scarf. Ning Sui couldn’t help herself: “That part isn’t very secure — be careful you don’t pull it off.”

“Hmm?” He looked up suddenly.

“……Oh.”

Ning Sui realized, only then, that she might have let something slip.

Xie Yichen released his fingers. His expression was indecipherable, one eyebrow raised: “I thought you bought this online?”

Ning Sui’s lashes steadied. Composure intact: “I did buy it online.”

Only the formulas were hers — she’d worked them in herself, one stitch at a time, pressing black wool through the knit with a crochet hook, which was why the attachment wasn’t very firm. The caramel scarf itself was purchased ready-made. The black yarn was also bought.

So technically — that counted as buying it online, in a way. Didn’t it?

Xie Yichen stared at her without blinking, then after a long moment gave a drawn-out “oh,” expression lazy: “Got it.”

“……”

What exactly had he “got” now?

Ning Sui let it go and opened Hu Ke’er’s message instead.

It was a voice note. She went to tap “transcribe to text” but pressed the wrong button — and Hu Ke’er’s enthusiastic voice suddenly blasted out at full volume: “Where did you put that black yarn — I want to come by your room and grab some to use for the arts department’s poster.”

Ning Sui frantically mashed the volume button to minimum.

Ahh ahh ahh, save her!

Last time Hu Ke’er had come to the dorm she’d spotted the yarn and asked about it. Ning Sui had deflected with “just a craft thing” and gotten away with it.

From the side, she felt a pointed, uninterpretable gaze resting on her. Ning Sui took a silent, slow breath, and looked up.

After a pause, she forged ahead with great conviction: “She’s singing. You know that Jay Chou song ‘Black Wool Sweater?’ “

And she hummed a few bars: “Black wool hidden somewhere deep, memories in my mind going fuzzy~”

“……”

Having finished her improvised performance, she didn’t spare a glance for Xie Yichen’s reaction. She flipped open the takeout container and took a long, decisive sip of the soup. Then she buried herself in the sweet and sour pork, cheeks puffing determinedly, eating as though she had a personal dispute with the food.

A good while passed. No sound came from the other side. Ning Sui was just about to say something when she heard Xie Yichen say her name: “Ning Sui.”

“Mm?” She looked up, mildly confused.

Through the window, the evening sky had gone a painter’s shade of orange. Ning Sui turned to look, her oval face pale and soft, the fine, downy hairs on her skin catching the light and glowing faintly gold at the edges.

Her lips were full and faintly rosy — like a peach, but softer.

Xie Yichen looked at that spot for a long moment. Then he reached out, quite directly, cupped her face in his hand, and let his thumb move slowly, deliberately across the corner of her mouth.

His voice dropped to something warm and a little rough: “You got some tomato sauce there.”