0x7a6f
Chen Weibin discovered the wallet address at 3:17 AM.
Winter in Cambridge darkens early, brightens late, with an unmeasurable gray in between. On his screen ran forty-three million on-chain data points, like a pot of boiling porridge, each bubble the moment someone somewhere pressed “confirm transaction.” Hesitation, greed, fear, boredom—all compressed into 0.0003-second hash values.
The address started with 0x7a6f. He later always felt 7a6f sounded like a kind of whimper, or like the sound of a delivery truck reversing at dawn.
0x7a6f’s trading pattern was strange. Not the bot-like, millisecond-precise wash trading, nor the retail-like, panicked chasing-highs-and-cutting-losses. It had a kind of. Rhythm. Before each large transfer, there was always a tiny test transaction, 0.0001 ETH, like someone dipping their toe in the water before jumping into a swimming pool.
Chen Weibin did the same thing himself.
He pulled out 0x7a6f’s transaction records and sorted them by time. 2 AM to 4 AM was peak activity. Beijing time 10 AM to noon.
He glanced at the time in the corner of his computer.
3:21 AM.
Xiao Xie had been in England for three months and still wasn’t used to the oyster sauce here.
“The color’s wrong,” she stood in the kitchen, holding a bottle of Lee Kum Kee, the smiling middle-aged man printed on the label, “Look, it’s too thin, like soy sauce diluted with water.”
Chen Weibin sat in the living room, laptop balanced on his legs, 0x7a6f’s transaction graph like an upside-down tree, roots reaching into unknown depths. “Then add more.”
“More and it’s too salty.”
“Then add less.”
“Less and there’s no flavor.”
They’d had this conversation many times, each one ending with Xiao Xie sighing. She said English markets were like morgues, all the vegetables lying there, dead but not yet rotting. She said she wanted to eat a live fish, not those frozen fillets cut into neat squares, but a fish that would jump, whose eyes still moved.
“You know,” she said, “Ningbo markets have this sound, it’s like…” She couldn’t imitate it, so she drew something in the air with her hand, like conducting an invisible orchestra.
Chen Weibin didn’t look up. 0x7a6f had sold their entire Maker position on March 17, 2024, at 3:03:47 AM. He flipped through his calendar—what day was March 17? He couldn’t remember. But he remembered that period he was writing a paper on MakerDAO, remembered developing an inexplicable weariness toward the protocol, a slightly numbing feeling that spread from his fingertips to the back of his skull.
From the kitchen came the “pop” of an oyster sauce bottle being opened.
He zoomed in on that day’s transaction records and saw 0x7a6f had hesitated for seven minutes before selling. Seven minutes, not long, not short, exactly the time it takes to steep a cup of tea and drink it.
He started building a profile of 0x7a6f.
This was his job. Turn forty-three million data points into 4,300 “user behavior patterns,” then classify those 4,300 patterns into seventeen “typical forms.” He was the anatomist, on-chain data the corpse, papers the autopsy report.
But 0x7a6f didn’t fit any typical form.
It was too much like a person. Not “like a human user”—all real users are human. But like “a specific person.” It had preferences: liked operating in the early morning, liked small test transactions, liked Curve but disliked Compound. It had habits: after each failed transaction, it waited exactly three minutes before retrying, no more, no less. It had… emotions? No, that word wasn’t right. It had fluctuations. Sometimes it would go fourteen days without any activity, then suddenly make twenty-seven dense transactions on a Tuesday afternoon.
Chen Weibin called this pattern “breathing.” In his paper draft he wrote: “This address exhibits activity cycles resembling circadian rhythms, with high-frequency trading periods alternating with silent periods, averaging 14±3 days.”
What he didn’t write: his own papers were written the same way. Fourteen days stuck on an opening, two days of furious 5,000-word output, then another fourteen days stuck.
Xiao Xie brought the dishes out. Oyster sauce lettuce, oyster sauce beef, oyster sauce mushrooms—she was clearly battling that bottle of Lee Kum Kee today.
“Do you eat spicy?” she asked. “I found a place selling chopped chili peppers. I don’t know if they’re authentic. Try some.”
She took a glass jar from the fridge. Inside were red flakes floating in oil, like trapped anger.
Chen Weibin scooped a spoonful.
Not spicy enough. But he didn’t say so. He swallowed it, the capsaicin making a small circle at the back of his tongue before disappearing, like an excuse that went nowhere.
“How is it?”
“Pretty good.”
“My mom’s asking when you’re coming back for New Year’s dinner.”
“The paper.”
“I know, I told her. She says take care of yourself.”
Take care of yourself. These four words traveled from Ningbo to Cambridge through fiber optics, routers, his ear canal, his auditory nerve, finally becoming a data format he couldn’t process. He didn’t know how to respond. His body was currently sitting in this chair, eating insufficiently spicy chili peppers, analyzing a wallet address with behavior patterns eerily similar to his own, and he wasn’t sure which one “take care of” was referring to.
One night in March, he had a dream.
In the dream he was in the People’s Bank office, where he’d worked seven years ago, only eight months. The office fluorescent lights always hummed, like bees trapped in the ceiling. His supervisor stood behind him.
“This variable name isn’t up to standard,” the supervisor said.
He turned around and found the supervisor’s face had become a string of hexadecimal code, 0x7a6f0e2b8c…
He woke up.
3:04 AM.
Instinctively he opened his computer and checked 0x7a6f’s on-chain records.
Three minutes ago, 0x7a6f had just completed a transaction.
In April, he started recording.
Not recording 0x7a6f. That was part of the research project, with protocols, procedures, ethics reviews. He started recording himself.
What time did he wake up? What did he eat? When did he feel tired? When did he feel hungry? When did he suddenly remember something from long ago? When did he want to open a particular website then close it?
He organized this data into a spreadsheet, then compared it with 0x7a6f’s transaction times.
The correlation coefficient was 0.73.
If he set a lag time of exactly eight hours—the time difference between Cambridge and Beijing—the correlation rose to 0.91.
He closed the spreadsheet and went to the kitchen to pour a glass of water.
Xiao Xie was already asleep. Her breathing came from the bedroom, even, like a properly configured sine wave.
He stood in the kitchen, the glass in his hand from IKEA, “Made in China” printed on the bottom. Outside the window was Cambridge night; in some building a light was still on. He didn’t know if it was a student pulling an all-nighter or a professor with insomnia or a light someone forgot to turn off.
He thought: If I open a trading interface now, if I buy 0.0001 ETH as a test, will 0x7a6f do the same thing eight hours later? Or is it the other way around—0x7a6f already did it eight hours ago, and I’m just repeating?
He didn’t test it.
He finished his water and went back to sleep.
In May, Xiao Xie discovered the fish in the freezer.
Not one fish. Fourteen fish.
He’d bought them from the Asian supermarket, frozen sea bass, each vacuum-sealed, like compressed data packets. He wanted to surprise Xiao Xie, wanted to say “Look, I found fish,” but he forgot he’d already bought thirteen, so he bought another one.
“Why did you buy so many fish?”
He looked at the neatly arranged fish in the freezer, like a transaction list in a blockchain explorer, each fish a transaction—timestamp, amount, hash value—everything recorded, but purpose unclear.
“I forgot.”
“You forgot you’d bought fish?”
“I forgot how many times I’d bought them.”
Xiao Xie looked at him, a look he recognized, the one when she was deciding whether to say something. Finally she didn’t. She closed the freezer door, and the freezer let out a sigh-like hum.
That night they ate one of the fish. Steamed, no oyster sauce—Xiao Xie said oyster sauce would overwhelm the fish’s freshness. He poured scalding soy sauce and ginger-scallion slivers over the fish, oil smoke rising, temporarily blurring his vision.
The fish was very fresh. He thought: if there were an address specifically recording “Chen Weibin eating fish” timestamps, what would the pattern look like? Fourteen fish, fourteen time points—could some pattern be derived?
He remembered 0x7a6f once repeatedly buying the same token on Uniswap, eleven times, each time the minimum amount, like some kind of repetitive behavior that couldn’t stop.
He took a bite of fish.
In June, he went to Edinburgh for a conference.
His collaborator was Scottish, with a four-syllable name he could never remember. They discussed paper submission strategy in a conference room, gray sky outside the window, like Cambridge gray but somehow different—wetter, or maybe he imagined it.
“This address is interesting,” the collaborator pointed at his screen, “How did you find it?”
On the screen was 0x7a6f’s transaction graph. He didn’t know when he’d added it to the presentation.
“Random sampling,” he said.
“Its behavior pattern is very much like a real person.”
“All users are real people.”
“No, I mean…” The collaborator scratched his red beard. “It’s like a specific person. Have you thought about tracing this address’s origin?”
He had thought about it. He had traced it. 0x7a6f’s first transaction was in November 2019, exactly two months after he left the People’s Bank. The incoming funds came from an exchange that no longer exists, no KYC, untraceable.
“Dead end,” he said.
“Shame.”
What he didn’t say: Shame about what? That he doesn’t know who this address belongs to, or that he suspects he does?
In July, he sent 0x7a6f an on-chain message.
This was possible: write a message in a transaction’s memo field, and it would be recorded on the blockchain forever, immutable, undeletable.
He wrote: “Who are you?”
Gas fee was 0.0007 ETH, about two yuan at the time. Two yuan for an eternal question.
He waited three days.
At 3:11 AM on the fourth day, 0x7a6f sent a transaction. Amount was 0 ETH, a pure memo transaction, gas fee paid for nothing.
The memo read: “What do you want to eat?”
He took the laptop off his legs, walked into the kitchen, opened the freezer.
Ten fish left.
He took one out and put it in the sink to thaw. Water from the tap ran over the vacuum-sealed bag, making a sound somewhere between “hissing” and “rustling”—he couldn’t name it, but the back of his neck prickled. That feeling again.
Xiao Xie’s alarm went off. 6:30, she had to get up to go to work at the supermarket.
“You didn’t sleep again?” She walked into the kitchen, saw the fish in the sink. “Fish this early?”
“For dinner.”
“It’ll spoil sitting there.”
“I’ll put it in the fridge.”
“It’ll still lose flavor in the fridge.”
He put the fish in the refrigerator, next to the bottle of Lee Kum Kee oyster sauce. The smiling man on the bottle looked at him, expression an unparseable symbol.
“I’m going to work,” Xiao Xie said. “What are you doing today?”
“Writing the paper.”
“Which one?”
“The data analysis one.”
“The forty-three million one?”
“Forty-three million seven hundred thousand.”
“What’s the difference?”
He thought about it. “Seven hundred thousand people.”
Xiao Xie tied her scarf, a red one they’d bought in Ningbo. He remembered that day was very cold but sunny, they walked down a street, and that street had a sound he couldn’t describe.
“What do you want for dinner?” she asked.
“Fish.”
“Fish again?”
“There are still ten left.”
She sighed, a sigh he knew well, somewhere between resignation and indulgence, an emotional fluctuation that could be recorded but not quantified.
The door closed.
He stood in the kitchen, listening to her footsteps disappear down the hallway, like a gradually weakening signal, finally falling silent.
Then he opened his computer and sent 0x7a6f a transaction.
The memo read: “Fish.”
Gas fee 0.0003 ETH.
Eternally, immutably, recorded in block 18,724,991.
He waited.
Outside the window, Cambridge was beginning to lighten, the gray gradually replaced by a paler gray, like oyster sauce with too much water added.
He didn’t know if 0x7a6f would reply, didn’t know what it would say if it did, didn’t know what he hoped it would say.
He only knew there were still ten fish in the freezer, a bottle of oyster sauce, and a question he couldn’t close.