The door is unlocked, admitting them with hardly a creak. In the sudden dimness, green and blue afterimages whorl across Kaelyn's vision. She suspects Valentine doesn't have the same problem since he moves ahead down the corridor without a moment of hesitation.

The telescope room has been re-purposed to suit its new occupants, with bays of blue-screened terminals circling the room in a labyrinthine pattern. Above them, the high-powered telescope looms while the gap in the domed ceiling casts a rectangle of light onto the floor.

At the top of the dais, a chair springs upright to release a gray figure. "When I first climbed this mountain, rising above the Fog, I thought to myself: now here's a metaphor worth taking in."

The figure steps into a square of sunlight, lighting the bare planes of their chest, and Kaelyn starts. A second gen synth. Not only an older model, but heavily modified beyond any Institute-approved configuration: bulbs jut from the back of the synth's skull and shoulders, and black duct tape covers sections where the artificial dermis has been stripped away.

Kaelyn glances between the synth and Valentine, the latter of whom narrows his eyes. In all their travels, they'd never encountered another self-aware gen two.

The synth looks from Kaelyn to Valentine, face going wooden with what could be shock. "Nick? It— it can't be you..."

Valentine's expression slides from surprise to suspicion. "Don't give me that. What are you trying to pull? I've never seen you before in my life. The only talking synth I know with a face that is the one I see in the mirror. Just who are you?"

Kaelyn can only look between the two of them as the strange synth, DiMA, tells his tale. He and Valentine had been the only two prototype synths ever built, the former permitted to develop his personality organically while the latter was implanted with a complete pre-existing one.

The synth's voice softens, trembles, as he says, "I saw you wake up not knowing who you were so many times... I couldn't let them do it to you anymore. You were my brother, Nick. I helped you escape the Institute. We left together."

Valentine is less than convinced. "If I were your brother, I'd remember!"

While DiMA's expressions lack the nuance of Valentine's, sympathy radiates from his frame. "That's where you'd be wrong. This happened over a century ago. There's only so much raw data that our prototype brains can hold."

Kaelyn laces her hands over her stomach, schooling her face to conceal her shock at it all. She steps closer to Valentine, lightly bumping his arm with her elbow so he knows she has his back.

A hundred years? Not sixty?

"Now that sure is convenient. But let me ask you something: can synths even be related? Just because we're from the same assembly line, does that make us family?"

DiMA's expression flickers, indecipherable. "Nick. I don't need you to believe me. I'm just glad to see you again. Now, if you'll indulge me with an answer, why did you come here if not to see me?"

The change of topic allows Valentine to ease back into his detective self. "We were hired to search for one Miss Kasumi Nakano and had reason to believe she made her way here."

"Ah." The word seems to carry more meaning than mere recognition. If DiMA is offended or hurt by Valentine's brusque professionalism, he doesn't show it. "Kasumi is here, safe."

"And your lot convinced her to make the journey here, is that right?"

"The choice was hers. Kasumi accepted our invitation to live here, as her true self, of her own free will."

Kaelyn hangs back while Valentine questions the other synth, playing sidekick, occasionally murmuring something to Valentine for him to ask.

Until DiMA's eerily familiar eyes sweep her over. "Pardon me for not greeting you sooner. You've entered a place of clarity. Understanding. Acadia welcomes you, as long as you welcome us."

Kaelyn holds up her hands. "I'm just Nick's partner. Not planning on causing any trouble for your people."

DiMA stares at her for a moment too long, tilting his head to the side. "If you'll indulge me with an answer: are you a synth as well?"

"No," she says, a shade too sharp. "It's not possible."

"Isn't it?" DiMA's expression could almost qualify as pitying. "A question, if I may. What is your earliest memory?"

It's old enough that all Kaelyn has are impressions and facts stitched together in an uneven tapestry: being told to hold Martin's hand on his first day of kindergarten, the tantrum he threw at the front door, then being pushed down the stairs.

Kaelyn's mouth thins. "That's none of your concern."

DiMA's expression never twitches but for the half-shuttering of his eyes. "I can see you're not ready to have this conversation."

There's no conversation to be had. Her life before the Great War, every moment she's survived since stumbling out of Vault 111, infiltrating the Institute for the Railroad—it simply isn't possible. "If I'm a synth, then the last few months have been nothing but a sick joke."

Valentine touches her elbow, his light touch doing more to ease the tension in her spine than words ever could.

DiMA's features soften. "Synth or human, Acadia will accept you for what you are. Now, about Kasumi..."

They find Kasumi in the power room, attempting to repair one of the generators. Even from a glance, the family resemblance is strong. Kasumi's straight black hair is neatly trimmed below her ears, contrasting with her soft fawn skin. She inherited Rei's eyes and nose, while there's a touch of Kenji in the quirk of her brow. Her well-loved coveralls are stained with grease, particularly on the legs.

Valentine clears his throat. "Miss Kasumi?"

She barely glances up from her work. "Yes? Sorry, this is being a real pain in the— ack!" The gear she'd been trying to fit pops free of its bearing.

Valentine crouches down beside her to grab the gear. "Need a hand? Those pre-war actuators can be real prickly."

Kasumi looks up and double takes. "Sorry. You're... not DiMA."

"You've got that right. Name's Nick Valentine. I'm a detective. Your folks asked me and my partner here to find you. You left 'em without even a note to explain."

Her hands still. "Look, my mom and dad— I mean, the people who took care of me. They wouldn't want me back. Not if they knew the truth. You have to know how people react to synths, right, since you're—you know?"

"You bet," Valentine agrees. "But not everyone takes it badly. Your folks are real worried about ya."

Kasumi sighs. "I thought it would be easier if I just left. How could I tell tell them 'Mom, Dad, I've been lying to you this whole time? Your real daughter is dead and I replaced her'?"

Kaelyn crouches down on Kasumi's other side so her voice won't carry. "You were isolated at your parents' house, so the Institute wouldn't have planted you there as a spy. If you are a synth replacement? If the original Kasumi was also mechanically gifted, the Institute might have kidnapped her for her ability. In that case, they wouldn't have killed her unless as a last resort." Kaelyn wracks her brain, trying to remember any Institute personnel who shared look or name with the girl in front of her. "The only other option is if your family took you in after the Railroad smuggled you to safety."

Again, Kaelyn wishes Valentine's memories if Kenji are clearer, if he can recall a daughter. If she had even been born at the time of the case.

Kasumi's no fool. Her eyes narrow and she looks between Kaelyn and Valentine. "How do you know all this?"

Kaelyn looks around the room. There are no corners in the circular architecture, but it's poorly lit save for the lanterns Kasumi has strategically placed. It buys her a few seconds to decide how much to divulge. "Have you heard of the Railroad? We help synths escape the Institute. That's how I know. But please don't spread that around. I'm still deciding how much I trust DiMA."

Interestingly, it's the latter part of her answer that connects with Kasumi. "You aren't the only one. I mean, I believe I'm a synth, but… there's something wrong. With Acadia. I'm not running this time. I came here for answers, and I'm going to get them. You saw all those computer's DiMA's hooked up to, right? They hold his memories or offload data from his brain. So when I was doing some repairs, I got curious…"

Kaelyn shivers in the shaded front of the observatory. Letting out a heavy exhale, she wraps her jacket more firmly around herself, picking at a loose thread on the hem. Her thoughts churn with all they've learned.

Valentine tilts his head back to watch a lonely cloud strafe across the sky. "So, DiMA's got his fingers everywhere on this island. We've gone straight from one case to a another. It's never easy for us, is it?"

Jerking her chin for Valentine to follow, Kaelyn makes her way through a gap in the chain-link fence and finds a spot on a flat outcrop with an unimpeded view of the island below. Thanks to the Fog, it's decidedly unimpressive. Valentine's gaze is distant, anyway, so it's unlikely he's noticed.

"Nick? Are you all right?"

"I'll keep. Don't worry." But his voice is more glum than she's ever heard it. "Just need to figure all this out. You know, I always wondered if the Institute made other prototypes. What happened to them, if they existed. If they were thrown in the trash like I was or scrapped for parts. But I never figured that someone wanted to bust me out. Or that they'd be some kind of—family." Valentine turns to her then and his uncertainty breaks her heart. "Do you think he really could be my brother?"

Kaelyn fiddles with the zipper on her jacket. "I don't know, Nick. The family resemblance is rather strong, but there's more to family than blood. I always that figured once the Institute was done toying with you, that's when they came for— for Shaun." His name burns her throat. She looks away, to the forest below, to hide the moisture gathering at the corners of her eyes. "Over a hundred years, Nick?"

He grunts, but there's an edge to it. "I don't know if I buy DiMA's story about only having so much storage space in the old memory drive."

They'd learned the purpose of the terminal suite in the observatory's main hall. Augmented by rows upon rows of blue-screened monitors, DiMA can transcend the limits of his original hardware and offload unwanted data, neatly sealed and preserved like walls of honeycomb.

If Kaelyn's being honest, she's jealous. To have the option to remove the memories you don't want—not lose them completely, but store them away in a box where they can't rattle and whisper...

"If it's true and you can only retain so many memories, then at least you'll forget me eventually." If anything, it's a comfort to know she doesn't have to worry about leaving Valentine behind to remember her until he stops functioning.

At first he's confused. Then suspicion, a familiar sight on a detective's face, creases the well-worn lines on his artificial dermis. "And just what is that supposed to mean?"

Kaelyn stops, pivots away on her heel so he can't see her face. "I'm going to die one day, Valentine. Most likely sooner rather than later. But you won't be haunted by me forever. You can forget me and move on."

"Now hold on just a minute." Valentine's steel hand closes around her arm, spinning her to face him, and he plants both hands on her shoulders. His fingers dig into her skin as he pins her under a furious yellow gaze. "I'll be the judge of what's worth remembering. Losing you— losing my memories of you would be..."

Underneath his anger is shock. The tight lines around his eyes deepen, not quite in the same arrangement as crow's feet but expressive all the same. Kaelyn's gaze is drawn to his lips, pressed into an uneven line that slants down at the corners.

She whispers, "Would be what?"

He clears his throat. "Look, doll. I know you're in a rough spot right now, but don't go writing yourself off like that."

"Okay."

"I mean it." He tightens his grip before releasing her, then adjusts his fedora so the brim shades his face. "Still, this is all a little premature. There has to be some kind of proof out there about any connection between me and DiMA. 'S not much to go on, I'll admit. Our best bet would be to keep looking into DiMA and Acadia."

In hindsight, a detective wanting hard evidence shouldn't come as a surprise.

Kaelyn touches his arm. "We've done more with less. We'll find the answers."

For the first time since they walked into Acadia, the tension eases from Valentine's features. "Appreciate it, partner."

The Fog writhes in the valley below, frayed by the sun before it can climb to their rocky perch atop the mountain. Without the Fog condensers, even this little haven wouldn't exist. If not for DiMA, humans would have already been pushed off the island.

Valentine watches her hands. "You haven't stopped fidgeting since we talked to DiMA. What's eating at you?"

Kaelyn exhales in a long rattling stream. She shoves her hands in her pockets, the casual gesture belying the tension that stiffens her spine. "Does DiMA go around convincing everyone that they're synths? I was in a vault until just a few months ago. I'm human."

She has to be, or else every argument with Shaun over the distinction between synths and Nuka-Cola machines is even more twisted in retrospect.

"I'd wager they don't get many human visitors," Valentine says. "Don't sweat it. There'd be nothing wrong if you are a synth, besides. We could keep going until Judgment Day. Although I suppose that may have already passed us."

Kaelyn makes an irritated noise. "Don't you start. I remember being released from cryo. The Institute knew I was human and they're the ones that should be able to tell, right? My earliest memory is of my brother pushing me down the stairs at kindergarten."

Valentine is quiet for a beat. Then: "You never mentioned you had a brother."

"It's not like it matters anymore. He's dead." She doesn't want to know how—in the bombs, or in the fallout.

"Now just hold on a minute. Just because he's gone doesn't mean he never mattered, or that what you feel doesn't matter."

She swallows around the lump in her throat. "Let's just go. Need to get back to the harbor before sundown."