Dr. David Langford stood in his bathroom mirror and did not recognize the face looking back.

It was his face. He knew it was his face. He had shaved it that morning. He had brushed his teeth with the blue toothpaste from the tube on the left. He had the same small scar above his left eyebrow from a childhood bicycle accident. But for a moment -- a single, terrifying moment -- he did not know who he was.

Not his name. He knew his name. Not his age. He knew that too. But his memories, his skills, his identity -- those were clouded. Was the memory of his seventh birthday party his own, or had he absorbed it from a patient? Did he know how to play chess at an intermediate level because he had learned it, or because a patient had taught it to him in a session three months ago?

David turned on the shower and let the water run cold. He needed clarity.

***

He had developed the condition three years ago, during an EEG experiment at the university. The lead researcher, Dr. Helena Voss, had exposed him to high-frequency transcranial stimulation beyond the consent parameters. David had refused to sign a form that would have given Dr. Voss rights to his neural data. She had done it anyway.

The result: an extreme form of mirror neuron activity. Through prolonged contact and deep empathetic engagement, David could absorb fragments of his patients' skills, memories, and emotional patterns. At first, he thought it was unusual empathy -- a known phenomenon among clinicians. Then he realized it was something else.

He began keeping a secret journal of his anomalies.

A piano melody from a patient in therapy for musical trauma -- a concert pianist who had fled Yugoslavia. David found himself humming it in the shower, his fingers moving on his thigh in the exact fingerings she used.

The taste of pho from a Vietnamese patient -- a recipe her grandmother had taught her. David cooked it one evening without knowing where the technique came from. He had never been to a Vietnamese restaurant.

The cursive handwriting of an elderly patient -- a loop he had never practiced. He caught himself writing in it during a faculty meeting and stopped, embarrassed.

***

Samantha "Sam" Cross was his most challenging patient. She had Dissociative Identity Disorder with seven documented alternate identities. Each identity had different skills, memories, and emotional patterns. She was the perfect storm for David's condition: every session with Sam exposed him to a completely different neurological profile.

After a session with "Ana," a 1940s-era child identity who spoke only Serbian, David woke up drawing Serbian Cyrillic letters on his bedroom wall.

After a session with "Milo," a protective alter who was a former Yugoslav soldier, David found himself checking the locks on his doors three times and sleeping with one eye open.

He was absorbing not just skills but personality fragments. His colleagues noticed changes. Dr. Marcus Chen, his colleague and mentor, asked if David was okay: "You seem more intense. More... scattered."

David could not explain.

Dr. Elena Vasquez, a neurologist at Northwestern, ran new EEGs and found that David's mirror neuron system was not just overactive -- it was rewiring itself, creating new neural pathways that connected to his own identity.

"You are literally becoming a patchwork of your patients," she said. "This is unprecedented. And potentially dangerous."

"What does dangerous mean?"

"If you absorb too much, there may not be enough of you left."

***

The boundaries between David's memories and his absorbed memories collapsed.

He remembered his college graduation, but could not be sure the memory was his -- a patient had described an identical ceremony.

He spoke English in a conversation with Marcus and caught himself responding in Serbian, the switch feeling involuntary.

Sam's alters began to address him by names that were not his. "You are not David," said Milo. "You are the room where we all live."

David stopped going to sessions. Marcus was concerned. Vasquez offered experimental treatment: a drug that suppressed mirror neuron activity. It would stop the absorption. It would also make David less empathetic, less able to connect with patients, less able to do his job.

David tried the drug for one week. He felt like a wall had been built between him and his patients. He was "stable." He was also miserable. He stopped the drug. The absorption resumed.

***

He found the news article about the EEG experiment from three years ago. Dr. Voss had been fired, but the damage was done. David's condition was not an accident. It was sabotage.

David sat in Dr. Vasquez's white room. The suppressant medication was on the table beside him. He had decided to stop seeing patients. He had decided to take the drug. He had decided to try to rebuild a self that was actually his own.

But before he did, he had one last session with Sam. He told her what was happening. Sam's alters reacted in different ways. Ana cried. Milo was angry. The therapist-identity was calm and said: "You absorbed us because we needed to be absorbed. We were trapped in this body and you were the only one who could hold us. Now you must let us go."

David picked up the pill. He was not afraid of disappearing. He was afraid of discovering that he had never been really there to begin with.

He took the pill, and the room began to fade at the edges, and he thought, perhaps, of the piano melody from Sam's therapist identity, and wondered if that melody was ever his to begin with.