A/N: I took some liberties with the science and the separate Earth thing so please don't crucify me. :) Warning for angst.
"So, run this by me again," Barry says, shaking his head in minor frustration when Cisco chuckles at his unintended pun.
"Barry," Caitlin says, almost incredulous, "you're a brilliant scientist, a meta-human yourself…"
"And you travel through time," Cisco interrupts. "I mean, it's confusing, but it's not, like, programming your DVR confusing."
"I know, I know," Barry says, "it's just…maybe it's more on the level of my head kind of gets it, but the rest of my body would rather not believe it's happening."
"I understand," Caitlin says, putting a hand on his shoulder, ready to launch into her explanation one more time – twelve more times, if that's what Barry needs. "So, we've already experienced the breach that leads to Earth 2, and then the one that leads to Earth 3."
"And those were fairly stable, right?" Barry interjects, finding comfort in the one piece of information he knows for sure.
"Yes," Caitlin says, "but these other breaches…whatever triggered the first two, whatever anomalies in time caused these gateways to appear, they've super accelerated, become massively unstable."
"But what changed? Why would the first two follow a…sort of pattern," he asks, using clumsy confused hand gestures, trying to clarify his point, "and the rest, just…"
"Appear?" Caitlin sighs. "No idea. We haven't been able to isolate a cause yet. Or a connection. The only thing we do know is that whatever is causing them to appear and disappear, it's degrading."
"Which means," Cisco continues before Barry has to ask, "when they close, they'll close up for good, and whoever comes over from them will be trapped here…indefinitely."
"And with no way to return them to their own Earths," Barry says, trying to sort the answer out in his head.
"History won't just be ruined," Cisco continues.
"It'll be obliterated," Caitlin finishes. "Everything will be chaos. It'll create holes in time, complete epochs could be erased."
"The Queen of England could disappear," Cisco elaborates, "and history could end up with three Hitlers, all with different personalities and motives."
"The Earth that we know, and every other Earth, could conceivably tear apart," Caitlin concludes. "Cease to exist."
Barry blows out a long breath, bent over Caitlin's tablet screen and staring at the interactive diagram she created of their Earth, Earth 2 and Earth 3, and the timeline of dimensions there after that are being created at a rate of almost a dozen per day.
"They're opening at random?" Barry asks, watching as the diagram shifts with the creation of a new Earth, and then again with the creation of three more.
"And we haven't been able to predict yet where or when," Caitlin says. "Or who might pop out of them."
"Like other meta-humans?" Barry guesses. "Ones we haven't seen before because they don't exist here?"
"Not just meta-humans," Cisco says. "But, like, dogs and cats and regular people."
"Okay," Barry says, not seeing that as a problem, "but that's not a big deal."
"It is," Caitlin corrects, "if we don't know who they are on their particular plane of existence."
"I don't follow," Barry says. "As long as they're not meta-humans, they're not dangerous."
"But meta-humans aren't the only people in the world that pose a threat. What about just regular murderers, psychopaths, and rapists?"
"Yeah," Cisco cuts in, "what if Jaleel down at Big Belly Burger is a serial killer on Earth 17, and she jumps over here for a visit with a side of a massive murder spree?"
"And what if people we know and trust turn out to be killers in their other worlds, and they come over here?" Caitlin offers. "People who know your secret."
"Like Oliver and Felicity," Cisco says.
"Or Joe," Barry says with a heavy swallow. "Iris…"
"Or you," Caitlin says.
"Yeah," Barry says, running a hand through his hair. "I see where you're going with this."
"God, my head hurts," Cisco groans. A klaxon sounds overhead, red lights flash, and Cisco winces. "And that's not helping."
"What is it?" Barry asks, following Caitlin as she turns to her computer screen.
"We have a visitor," Caitlin answers.
Barry peers over her shoulder, his face pinched into a scowl.
"Snart," he spits at the image of the man riding the elevator. He's not mugging for the camera, obnoxiously smug as usual. Instead, he's smoothing out his jacket and adjusting his cuffs, peering at his reflection in the elevator wall's smooth surface and fidgeting a great deal over his appearance.
Barry leans closer, trying to figure out…is that…an Armani suit he's wearing?
Barry watches Snart leave the elevator, following him from security screen to security screen, strutting down the corridor like he owns the place. He steps around the corner and into the lab, raising his head with what looks deceptively like a warm smile for the three scientists standing defensively behind their control panel, trying to anticipate this criminal's next move.
"Hey, Scarlet," Len says, his eyes and his smile on Barry and only Barry.
"What are you doing here?" Barry demands, his voice simmering around a low, menacing growl.
"Well, hello to you, too, handsome," Len says and there it is – that smug smile that Barry detests, but Snart takes it a step further by nodding at Caitlin and Cisco. "Hello Cisco, Cait. Don't you look stunning today?"
"Uh…thank you?" Caitlin says, shooting a look at Cisco, who returns it with an eyebrow cocked.
"I said, what are you doing here?" Barry snarls, and Len's brow pulls together. Barry steps out from behind the panel as he examines Len's face. Len looks…confused. Barry waits for the snappy comeback, but he never makes one.
"You…told me to meet you here," Len says with a chuckle that can almost be construed as nervous. "For lunch. You said you couldn't come at noon today because you had a meeting with Joe."
Barry doesn't respond, but he can't look away. He's waiting for the…the whatever. Ice grenades, maybe from his cufflinks; laser ice beams, possibly from his lapels; a full scale assault of the lab, or of Joe's house, or Cisco's parents' house, by Snart's Rogues Gallery. As Barry waits for another klaxon to sound, an alert on their security screens, with Cisco and Caitlin anticipating the same behind him, Snart's questioning eyes bounce from face to face, with none of his usual condescension, none of his usual swagger.
And that makes Barry more unnerved than ever.
"Is this about last night?" Len asks, lowering his voice on the last two words. "Because I thought we decided to put that behind us. Start over fresh."
Barry doesn't have an answer for that. Another five minutes rolls by and nothing – nothing on the scanners, nothing from the police station, no 9-1-1 texts from Iris or Joe. Barry has no idea what Snart could be playing at, but this has gone far enough.
"Come on, Bare," Len says, reaching out a hand as if he's going to take Barry's.
"Stop calling me that," Barry snaps, pulling his hand away and taking a step back.
"Don't be like that," Len says, stepping forward, trying to get Barry to let him in. "Can't we go somewhere else and talk about this?" Len looks over Barry's shoulder at Caitlin and Cisco, staring at him and Barry with matching blank expressions. "Maybe somewhere private?"
"Yeah," Barry says, rolling up his sleeves, lightening sparking in his eyes. "I'll take you someplace private."
Caitlin and Cisco both look away as a flash of red lightening fills the room. The air inside sucks out, papers fly, and when they turn back around, both Barry and Snart are gone.
"Barry?" Len pounds his hands on the glass, looking up and around at the enclosed room he's in, barely ten foot by ten foot, way too small for comfort. "Barry, let me out."
"No," Barry says, pacing back and forth, trying to decide between questioning Snart, trying to find out what his angle is, and just leaving him here to rot. Barry always said these prisons were made for meta-humans, not humans, but he might be willing to make an exception in Snart's case.
"Well, can you at least talk to me about why you've decided to lock me up in here?" Len asks. "Because, I know you, Barry, and this isn't like you."
"You don't know me," Barry says, his tone a threat – an undeniable one. "You don't know me at all."
"Yes," Len says, running his hand down the glass. "Yes, I do. I do know you. I know everything about you. All of your secrets. You trust me, Barry."
"No! I did trust you!" Barry growls. "When the chips were down, I went out on a limb for you! I trusted you, and you betrayed us!"
"When? How? I…I don't know what you're talking about, Bare!" Len says. "I really don't! But, let's talk about it. Just…please, let me out."
Barry shakes his head. He doesn't like being toyed with, and this joke, whatever it is, has gone on too long. Barry turns on his heel and heads out of the Pipeline.
"Please," Len calls after him, his normally smooth-under-pressure voice sounding vaguely panicked, "let me out."
"You want out, let yourself out," Barry snaps.
"H-how?" Len asks, looking around the seamless room.
"You'll think of a way," Barry says.
"I won't, Bare!" Len says. "I…I don't belong in here! I'm not the Silver Skulker, or Willow Wisp, or one of your other meta-humans."
"Nice try," Barry bites back, "but Cisco gets to name the meta-humans."
"I know," Len says in defeat, watching Barry leave. "He did. I was there."
Barry stops, their conversation from before Snart arrived about other meta-humans on other Earths ringing in his ears. But Barry still isn't buying this. Snart's pulled too much crap on them before for Barry to believe it.
Too much for Barry to sympathize.
"This is all a very convincing act," Barry says, turning back to the prisoner in his cell, "and if you were anyone else, I might feel sorry for you. But you said it yourself, you're a criminal and a liar, and that's all you'll ever be."
Len nods. He looks away. "When you look at me, that's all you ever see," he says. "I guess you're right."
"Yeah," Barry agrees cruelly, even as Snart deflates against the glass, the lost look on his face pulling a single string around Barry's heart – his do-gooder string, Snart once called it, explaining, as he held him at gunpoint, that it's the reason why Barry's always destined to fail, "you bet I am."
"No," Caitlin says, rushing in, "you're not."
"What?" Barry asks. "Wh-what do you mean?"
"I mean this," Caitlin says, handing over her tablet for Barry to see. "This is a scan I did of Snart in his cell just a few minutes ago."
Barry can see that, but whatever's gotten Caitlin so agitated is not blaringly obvious to Barry.
"What am I looking for?" he asks.
"This," she says, swiping a finger across the screen and bringing up a split screen with a second scan, side by side with the first, of the same anatomical form, but the image blotched in sections by a glowing white-blue mass that seems to bleed around the figure, through the veins and arteries.
"Where did you get this?" Barry asks, looking at the first scan, then the second.
"It's a scan that Joe had Cisco do of Snart before you tried to relocate the meta-humans."
"But we promised Snart that we'd destroy all of his records," Barry says, not thrilled about going back on his word, not even to a villain like Snart. "Make him disappear."
"Well, Joe never trusted him. This was his insurance policy, in case something went wrong. It's all of his information – blood type, DNA, retinal scan, digital fingerprints, the works. He left you out of the loop because…"
"Yeah," Barry says, still stung by that failure. "I get it."
"Hey" – Caitlin puts a comforting hand on Barry's arm – "they left me out, too."
"Yeah, but you didn't mess up as epically as I did."
Caitlin sighs. "Barry…"
"So, what's going on here?" Barry asks, eager to get away from the topic of his screw ups and back on track. "Why is this scan different?"
"These areas of white, they're a byproduct of his cold gun, a sort of waste created by the effect of the gun's creating an atmosphere of absolute zero. It's like GSR, except in the case of the cold gun, the byproduct didn't just stay on his skin and get washed off. It leeched into his system."
"But, we've all fired those guns, and as far as I know, we don't have it."
"Because we didn't use them as much as Snart does. In this scan of Snart, it's pretty much flowing through his body, attaching to molecules and changing them as others return to normal, like a constant molecular reaction firing off within his blood and organs."
"Will it kill him?" Barry asks, peeking up at Len, who's lost interest in the conversation he and Caitlin are having, and is staring down at his shoes.
Not lost interest, Barry realizes. Lost hope. Leonard Snart, the infamous Captain Cold, vanquished, his head leaning against the glass, eyes focused on the floor, looking positively resigned in his inescapable prison.
Not like Snart at all, who's always scheming, always planning.
Always one step ahead.
These cells were retrofitted to contain the meta-humans, and they've done their jobs well.
But truthfully, Barry never imagined it would be able to contain Leonard Snart.
"No," Caitlin says. "No, it shouldn't be fatal, but that's not the point. This Snart" – she gestures to the despondent man in the cell – "has none of the same reaction in his body. Not even a trace." Caitlin catches Barry's eyes. "He's never fired one of those guns. He's completely clean."
Barry shakes his head in disbelief. No. That can't be possible.
"Well, maybe he's developed some kind of…"
"No," Caitlin insists. "The technology that could completely erase a signature of that magnitude hasn't been invented yet. This isn't our Leonard Snart."
"No," Cisco agrees, coming up behind with his own bomb to drop. "He's…your…Leonard Snart." Cisco holds up a phone – an iPhone Cisco found in the aftermath of Barry's rush to lock Snart up, the lock screen a picture of Len and Barry, smiling together, wrapped in one another's arms.
And they're kissing.