Aaron walked down the corridors like a man who had made peace with his circumstances.

Not genuine peace. The kind of peace that is actually just suppressed chaos wearing a calm expression and hoping nobody looks too closely.

First right, then left, then straight, then at the dead end make another right. Those were Ariana’s directions, delivered over the telephone with the cheerful efficiency of someone giving instructions to a food delivery person, except the delivery in this case was Aaron himself, reporting to a location he had not freely chosen to report to.

He followed the directions. He arrived.

And then he stopped.

The door in front of him was enormous.

Not large-door enormous. Not impressive-building enormous. Enormous enormous — the kind of door that made you instinctively look around for whatever it had been built to contain, because whatever that thing was, it was not human-sized and probably not friendly. Aaron had watched enough science fiction films in his previous life to recognize the specific style of hatch currently blocking his path. Thick. Circular seams. The unmistakable design language of we built this to withstand things going catastrophically wrong inside.

He stared at it for a moment.

What exactly were the Oscar’s House of Science people doing in here? The door was big enough to comfortably admit something the size of a blue whale. Were they experimenting on blue whales? Was that a thing that happened? He filed the question away without answering it, because some questions were better left unasked in facilities you’d been blackmailed into attending.

He found the fingerprint scanner — same model as the one outside his room, now with the addition of a brief personal history between them — and pressed his palm to it.

The console flashed red.

Aaron looked at it.

The console appeared to reconsider. It glitched, cycled through some internal deliberation, and resolved itself into blue.

A hissing sound filled the metallic hallway, deep and pressurized, like the sound of something that had been sealed very thoroughly beginning the process of becoming unsealed. The enormous door began to move, pulling apart from its frame with the slow, self-important pace of machinery that knows it is impressive and sees no reason to rush.

Aaron could see the partition now — thick rubber lining running along the full circumference of the seal. His earlier guess confirmed. The inside of this lab could be fully isolated. Could be turned into a vacuum if something went wrong, or if someone decided a vacuum was the appropriate response to whatever was happening in there.

The door was opening at the pace of a glacier with somewhere to be. But the gap between frame and door was already enough — ten, maybe twenty percent open — and Aaron was not a blue whale. He slid through the gap without difficulty and stepped inside.

Behind him, the door decided it had been open long enough.

It slammed shut with the kind of force that is less a sound and more a physical event. The air moved. The floor registered it. Aaron, who was no longer in the path of it, felt it anyway and had the very clear and visceral understanding that had he been standing in that gap two seconds longer, whatever remained of him would have been a very well-pressed version of his former self.

He took a breath and looked forward.

Ariana was sitting on a table.

She had changed into her professional configuration — white lab gown, black stockings, her brown hair with those lighter highlighted locks falling around her shoulders, and the sunglasses still sitting on the bridge of her nose as if they had a permanent residential arrangement there. She watched him walk in with the composed attention of someone who has been waiting but would never admit to being impatient.

Aaron’s brain, operating independently of his better judgment, processed the visual information in front of it and arrived at a conclusion that his better judgment immediately flagged, reviewed, and rejected on firm biological grounds.

The woman was objectively, undeniably, almost unreasonably attractive.

He was also, with equal objectivity and zero ambiguity, her biological brother.

Step-sister would have been a different conversation. Adopted, distant cousin, vaguely-related-through-marriage — the moral calculus shifted considerably in those scenarios. But biological? That was a clear line. A non-negotiable boundary. A wall that existed for good reasons that humanity had collectively agreed upon over a very long time.

Aaron locked every associated thought in a mental box, put the box in a mental room, closed the mental door, and walked forward like a completely normal person with no complicated internal situation whatsoever.

"Ready, little brother?" Ariana smiled when he got close enough.

He looked around the lab instead of answering, which was both a deflection and a genuine survey of the environment.

The place was stocked with the enthusiasm of someone who had been given a large budget and no instruction to show restraint. Microscopes. Enormous glass tubes. Burners. Vials of chemicals in colors that didn’t exist in nature and were probably the reason the door had a vacuum seal. Random animal organs, preserved specimens, corpses of creatures he didn’t recognize. Unique plants in various stages of being studied. Technological equipment whose purpose he couldn’t begin to guess at.

It was the kind of room that Bella would have walked into and immediately started asking seven questions simultaneously. Aaron was not Bella. What mattered to him right now was considerably simpler.

"Is it just us here?" he asked, doing a casual sweep of the room that was not casual at all.

"Yep." Ariana didn’t move from the table. "This is my private research. Do not worry — I am not going to share my results with the higher-ups. Not with your identity, at least."

"What do you mean?"

She closed the distance between them in a single step. 𝗳𝚛𝗲𝕖𝚠𝚎𝚋𝗻𝗼𝕧𝗲𝐥.𝚌𝚘𝐦

Aaron’s instincts fired before his conscious thought did. His hand intercepted her incoming reach — she had been going for his sunglasses, a swift and unbothered attempt to simply remove them — and he redirected it without thinking, the whole exchange happening in the span of less than a second.

Ariana pulled her hand back, looked at the space where her grab had been, and made a sound that was part impressed and part something else entirely.

"Ah damn, nice instincts." She said it with a lick of her lips that Aaron filed into the same mental box as everything else from the past thirty seconds.

She didn’t try again. She settled back into her composed stance and continued as if the attempted theft of his eyewear had been a brief, unremarkable interlude.

"Whatever you show or do will only stay with me. The results of the experiments will be shared, but your identity won’t be."

"You’re contradicting yourself." Aaron narrowed his eyes.

"I am not." She fixed her glasses with one finger, the gesture carrying a particular kind of patience. "I am telling you that I am willing to protect your identity. But the results of the experiments — I cannot protect those, since I am permitted to do this research for a reason."

She paused.

"So. Long story short — no one will know who the volunteer is, but they will know what he is."

She delivered this with a small shrug, the specific shrug of someone conveying that the distinction seemed reasonable from where they were standing and if he disagreed, that was a him problem.

Then she rubbed her hands together.

It was the hand-rub of pure, undisguised anticipation. The kind of gesture associated with people who have been looking forward to something for a long time and have now arrived at the moment of beginning. It was, frankly, the kind of look that belonged on someone making a deal rather than someone conducting science.

"Are you ready to begin, brother?" She purred.

"How can I believe you?" Aaron said flatly. "Give me proof."

While he said it, he was running his instincts at full capacity, sweeping the room in every direction for the feeling of being watched, for the intent of hidden recording equipment, for anything that would give him a concrete answer one way or the other.

He found nothing.

He swept again. Nothing.

Every direction came back empty, clean, surveillance-free. It was, paradoxically, more irritating than finding cameras would have been. Finding cameras was confirmation that the world operated predictably. Finding nothing when he expected something felt like the universe was withholding information.

"Well," Ariana giggled, watching him with the amusement of someone who knows exactly what you’re doing, "you can detect the cameras yourself — why should I bother proving it? I assure you that you won’t find a single camera around."

Aaron looked at her flatly.

"Of course I saw how you took down all the hidden cameras in your bathroom," she continued, without a trace of embarrassment about the fact that this sentence confirmed she had been watching him do it. "That’s how I knew you could detect them."

He walked a full circuit of the room anyway. Corners, wall junctions, behind the larger equipment, anywhere that offered concealment. He was thorough. He was methodical. He was increasingly, grudgingly forced toward the conclusion that she was telling the truth.

And then he felt it.

A secondary sensation. Separate from his sweep of the room. Distinct, directional, and coming from somewhere specific.

He turned. Crossed the room in a few strides. Moved aside a beaker that had been sitting on the bench with the slightly-too-deliberate placement of something positioned to conceal rather than to be used.

Behind it was a mobile phone.

Sitting face-up. Wallpaper visible.

The wallpaper was a photograph of Ariana. A very good photograph of Ariana, of the kind that people select for their own phone wallpaper when the phone belongs to them.

Aaron picked it up, held it, and turned to look at her with an expression that the sunglasses concealed but the silence communicated perfectly.

Ariana raised both hands.

"My bad." She had the audacity to look only mildly apologetic. "I just wanted to test your freaky camera radar first."

A beat.

"After all," she added, the smile returning to its natural position of maximum self-satisfaction, "you agreed to be my lab rat."