Chapter Text
"Hey. What are you thinking about?"
"Quantum theory."
Erin made a noise.
"Urgh. I love quantum theory. "
"I love that you get so excited about quantum theory."
"Bubble or parallel?"
"I don't want to guess. I want to know. I want to break the barrier."
"Sometimes, I'm not sure if you're joking or not."
Holtzmann shook her head.
"You really are crazy."
But there was a delighted smile on her face when she said it.
"I know."
Holtzmann grinned back at her and Erin felt a surge of affection. Her own resident mad scientist.
"Check this out."
Erin followed Holtzmann's finger across the screen.
"It's… Some sort of E8 model..? Nono, wait… There should be another particle for that…But..."
She went to the blackboard and started jotting equations down, forehead scrunched up with concentration. She was oblivious to Holtzmann's eyes on her, leaned forward over her desk in anticipation. She stopped and slowly finished her last calculation.
"God, Holtz… This is crazy."
Erin stared at her with a hand covering her mouth, eyes wide. The expanse of Holtzmann's mind gave her vertigo sometimes.
"You're a genius. You know that, right?"
Holtzmann shrugged.
"It's a little quirky, but could get you closer to a Theory of everything if it works."
She said it like it was nothing. Erin's eyes were suspiciously moist. Holtzmann had shown her this amazing, possibly ground-breaking thing. She felt exhausted just from thinking about the possibilities if further calculations took them in the direction Holtzmann had shown her.
She switched to another simulation. Erin felt an irrational panic that she would never get to see the other one in its perfect particular symmetry again.
This one was different. Engineery. She was a theorist: she knew she would probably not understand all aspects of this one, since it was about function. But as an experimental model, it blew her mind, as everything Holtzmann did.
The next one was different again: little earths; a multitude of perfect globes multiplying, slight variations expressed mathematically floating across the screen.
Holtzmann pointed to one of them.
"What are you doing in that one?"
"What do you mean?"
"Erin Gilbert, parallel universe, any possible outcome. What are you doing?"
"You want to know what I might... do in a parallel universe? Me, personally?"
Erin was taken aback by the change of perspective from the known universe to her known universe.
Holtzmann nodded enthusiastically.
"Still working at Columbia, possibly…? The variations are likely small, so..."
"Unacceptable. They did not appreciate you."
Holtzmann put an arm around her shoulders.
"True."
Holtzmann could make her feel like that in a split second. Special. Like she truly was too good for Columbia.
"You're obviously working for Cern in one of them."
"This is probably gonna come as a huge shock to you, but I don't exactly do well with authority figures. So there's probably at least one where I'm fired from Cern."
Erin pulled a face.
"I know the feeling."
"Except it would totally be my own fault."
Holtzmann squeezed her shoulder. That was the thing about her: she seemed like this weird eccentric, too busy causing explosions with childlike glee to care about trivial stuff like Erin's feelings. But sometimes, Holtz was the only one who heard what Erin was actually saying, not just the words. She was happy she got fired. She was even happier she was a ghostbuster. But she still remembered the feeling in her body walking down the hall of shame with her cardboard box of sadness.
They spend the night shifting between universes. She had the strange feeling that Holtzmann was possibly more interested in Erin's universe than the limits of the known one. There was so much about Holtzmann and her universe she didn't know. Brilliant scientist and maker. Loyal friend. Reckless. Fearless. Fiercely protective. Quirky dresser, eccentric dancer. Gay. Tactile. Brutally honest. Truly able to be happy for other people. Then what?
"I might be a destitute artist."
"Artist…? Really?"
"Yup. Went to art school briefly, in Copenhagen. But for some reason, they didn't consider building a small reactor on school premises art."
Holtzmann rolled her eyes in an exaggerated manner. Erin laughed and made a mental note to have her show her whatever skill obviously got her into art school.
She pointed to the screen.
"In the best possible world, what would you do?"
Holtzmann was quiet for quite a long time. She thought to herself that this world, right here and now, might be the best one. Being a ghostbuster. Having friends. Sitting so close to Erin. Always Erin. She was her best world.
"I like this one."
That's what she said. Not "I love any world where I know you. There are probably parallel worlds where I don't, and it kills me. Being without you is the worst thing I can imagine." She didn't say that part. She wasn't that crazy.
Holtzmann's arm stayed around Erin's shoulder. Her hand gravitated to her neck. As they talked, she started to move her thumb along the base of her skull. Erin's focus shifted. She was still there with Holtzmann in the weighing of theories, but thirty percent of her brain was shut down to leave room for the warm sensation of the caress. Erin had no idea how starved she was of physical affection before meeting Holtzmann and her hands-on, tactile personality. Possible scientific breakthrough and Erin Gilbert worried that Holtzmann might stop touching her. Holtzmann did strange things to her priorities.
***
Erin slept badly. But not in a bad way. Holtzmann's model wouldn't leave her alone. And she couldn't stop thinking about what would happen if you could see the other side of that barrier. Was it even possible to express mathematically? She couldn't wait to continue the conversation.
Holtzmann was listening to Pretenders, precariously dancing with a cup of hot coffee in her hand. She smiled at Erin and lip synced to the words with exaggerated motions.
Don't get me wrong… I see neon lights, whenever you walk by.
Don't get me wrong… If I'm acting so distracted. I'm thinking about the fireworks, whenever you are near.
"I've done some calculations on that model you showed me."
"I love it when you talk dirty."
Holtzmann pulled some of her own calculations up on her screen and Erin frowned as she compared them. Quickly, she went over to her whiteboard and wrote something down. When she turned around Holtzmann was staring at her, head rested in her hands and the hint of a smile on her lips.
"What?"
"Just watching your brain."
Erin shook her head and smiled. But she loved it. She loved how the other ghostbusters got her. How Holtzmann understood what she was doing. How she could reveal herself in all her awkward geekiness and still be liked. She hadn't realized it at the time, but she had been intellectually starved when she worked at Columbia.
***
"Before being haunted, my dream job was astronaut."
"Obviously."
It was Friday night and both were too tired to make other plans than drinking bad beer sitting on the old lab couch. Or, Erin was too tired. She could have sworn that Holtz had some lecture she wanted to go to or something like that. But she didn't question her, she was just glad of the company.
They ended up talking about alternative worlds again.
"You too?"
"Probably dreamed more about building starships than being in them… Besides, you'd make a better astronaut than me. Lots of protocol to follow. You're protocol girl, not me."
"You're walking chaos theory, Holtzmann."
"I'll have you know that my tools are very well organized."
"Not sure organized is the term I'd use."
"You just do not get my system."
"Is chaos a system?"
"I'd die to get to work on the ISS. I have some ideas for improving their machinery."
"You'd build a reactor, put it on a shuttle, wait until an alien came along and give it the keys?
"Ha. Funny. You're a funny woman. I like that."
Erin still enjoyed making good-natured fun of Holtzmann for leaving the keys in the Ecto1 to be stolen by a joyriding ghost.
"I did write to them a while back, with a few suggestions."
"Oh no, you don't. We need you here. No space station for you."
"Don't worry, I'd keep in touch."
"Really? How exactly would you keep in touch from the space station?"
"You can call people. At least family. So maybe we'd have to get married."
Holtzmann winked at her.
"Unless we both lived there. Then we could just talk to each other at the end of the day like normal married people, before we do the falling asleep standing up thing."
Erin was taken aback. Holtzmann had always flirted a little in her quirky way. But married…? Wow. She didn't know what to say.
"Would they even let a married couple go up together?"
That was not what she intended to say. At all. But it wasn't the first time Holtzmann made her surprise herself.
"Guess we'll have to get married and ask them."
"Funny, Holtz."
Erin changed the subject. It felt safer.
"Apparently you know a lot about cadavers, so you could be a coroner, or something else appropriately ghoulish."
"You can follow rules, so you could be law enforcement. FBI. We could investigate the paranormal together."
"You realize you made us into Mulder and Scully, right?"
"Umm… That may have been on purpose. Love that show."
"The whole show, or just Scully?"
Holtzmann smiled. Erin knew her better than she let on.
"Both. Scully, OBVIOUSLY. But both."
"Well, we're already investigating the paranormal, so..."
"Exactly. Another beer, Mulder?"
"Apart from the cadaver thing, I'm pretty sure you're Mulder."
It wasn't the first time Holtzmann made them a couple. Maybe she shouldn't indulge her, but there was a disarming quality to Holtzmann's flirting, like it was too blatant and too obvious to be an issue. Besides, Erin liked it, even if she didn't give Holtzmann the satisfaction of knowing that, it would make her way too cocky.
"Then there's the time travel aspect."
Holtzmann says it like it's nothing. Time travel. Erin feels her heart start pounding fast. She's been thinking about that. Even done some pretty unorthodox calculations. Holtzmann's model opened so many possibilities up.
"I've been skeptical, but I'm not so sure now. I mean, we did see a ghost try to ruin New York and I went halfway through a portal to some yet unspecified 'other side', so… We should do some more calculations on that, by the way."
"You have to tell me about it some time."
"I showed you the first theory. That's pretty much how far I've come."
"Not mathematically."
"Oh... I was pretty focused on Abby. I was a bad scientist."
"And a really good friend."
"In some of these worlds, Abby and I probably didn't make it back through the vortex..."
Holtzmann grabbed her hand and squeezed it. Hard. Almost too hard to be pleasant.
"Don't want to talk about those."
Holtzmann didn't let go. For the rest of the conversation, Erin's hand was in hers, in a firm grip.
***
It turns into a game. A ritual, even. They would end up engrossed in alternative worlds and the role they would play in them. They were both aware, as scientists, that they had gotten far away from quantum theory by now. It had started out as work, or at least science. Now it was somewhere between an immensely enjoyable game and… something else? Erin wasn't sure how to define it, she just knew she had become addicted to spending time in the alternative worlds of Holtzmann's mind. Or maybe just to being with Holtzmann in this world. She was the most brilliant and unconventional mind she had faced. And she wanted to talk about Erin. Not about how she might revolutionize experimental particle physics. Just about Erin. What would Erin do, or think, in a certain situation? That was the most important find of all to Holtzmann.
They're sitting on the floor, facing each other. Their knees are touching, barely. Erin never sat on floors, before Holtzmann. Abby said that Holtzmann never used to be still, the way she is with Erin. Erin doesn't know what that means, if anything. But she likes it.
They've both been a bit obsessed with time travel lately. Unsurprisingly, Holtzmann wants to be a pirate. Erin didn't even have to wait for it to know she was going to be cast as Holtzmann's wench. She objected and Holtzmann begrudgingly demoted Abby and made her first mate instead. They both agreed that Patty would make an awesome, fearsome pirate.
Holtzmann goes to the old west next. Erin knows she was going to be a renegade gunslinger before she says it, it makes sense. Erin wants to be one too, even though she suspects it's more likely that she'd be the town schoolteacher. But Holtzmann puts her behind the saloon bar and winks and says she'd come in for a drink every single night.
"Why can't I be the gunslinger? And you be the barmaid?"
"Excuse me? Who makes guns, you or me? Who teaches whom to shoot them?"
"Fair point. But you'd make a good barmaid."
"I would make a TERRIBLE barmaid."
"You'd sell so much booze, though,"
Holtzmann hiked her eyebrows up.
"I would…?
"Well, you're really pretty, so people would want to talk to you…"
"Oh."
Erin had never voiced the opinion that Holtzmann was beautiful before and now her colleague seemed like she didn't know what to do with the information. But it was just an objective fact. Holtzmann was gorgeous.
Erin looked away, self-conscious. She took a sip of the wine Holtzmann had brought. She was such a dark horse: it was really good. Erin almost lost focus on the rest when the first mouthful exploded on her tongue. It was Friday night, and Erin was feeling a subtle but pleasant buzz as the second glass worked its magic. The heavy red played tricks on her tongue. Like telling Holtzmann she was pretty.
The date-like quality of the evening was not completely lost on her. Alone in the fire house, drinking, the leftovers of dinner on the table, lights dimmed for atmosphere. Except in their case, dinner-and-movie was dinner-and-parallel-realities. She and Holtzmann weren't lovers, they were just colleagues and friends. Close friends, but still. Holtzmann knew she wasn't gay. She shook the feeling, or tried to, as Holtzmann's fingers brushed hers while she was excitedly telling her a story about something Rebecca Gorin had said about string theory. Gorin was not a fan. It was pretty funny.
They were sitting curled up on either end of the second-floor lab couch now, Erin yawning occasionally, cradling a third glass of wine in her hand. It was after midnight. Holtzmann had left the future behind and was talking about the more recent past. Erin wasn't sure she liked the story much.
"Could have lived in Honolulu, I guess."
"Hawaii?"
"There was this girl I met in college. She was serious about us but I kind of didn't get that until much later. So, guess I might be living in Hawaii in one those worlds."
Erin frowned. A world where Holtzmann was married, but didn't joke about it being to her.
"Did you… Did you like her enough to marry her?"
"I was too young to know what I wanted and she was much older than me. Maybe if we'd met later."
The frown deepened. She didn't know why she hated the idea of Holtzmann getting married in college and moving to Hawaii. She decided that it was about waste of talent. Holtzmann belonged at Cern. Or here, with them. Mostly with them. They needed her. Erin needed her.
***
The following night, Erin was moving through the dark, quiet fire station. She couldn't sleep. She didn't turn any lights on: she liked it in the dark, just the street light making shadows. Something was keeping her up and annoyingly, she couldn't pinpoint what it was. There was just this feeling, this idea in the back of her mind and it refused to move into her consciousness. She was almost sure it wasn't work related: everything had gone almost disconcertingly smoothly since they saved New York city.
"You carry a lot of tension in your shoulders."
Erin jumped.
"Jesus, Holtz."
"Sorry."
But Erin could hear from her smiling voice that she wasn't. Holtzmann rarely was. Her hands landed on her shoulders and Erin moaned as she kneaded the tense muscle.
"Sit."
She did, gratefully. Holtzmann had magical hands. They built beautiful, lethal things and had an immediately calming effect on Erin.
After she finished, Holtzmann's hands rested lightly on her warm, relaxed shoulder. Erin had the feeling that something else should happen now. That she should turn around and… do what, exactly? There was something in the thick silence that suggested that Holtzmann was waiting for something too. But how do you express something you can't define yourself?
She said goodnight. But she didn't want to go. Holtzmann lingered. They spent almost an hour in another world, where Erin for some reason worked in a post office and Holtzmann was a mailman. They laughed at how none of them could quite explain how they ended up there or why. Erin went to bed and watched the sun rise, thinking about how she liked the way Holtzmann's nose scrunched up and her eyes became even more cat-like when she laughed.
***
Erin had developed a disconcerting habit of staring at Holtzmann. She was aware that she was staring, but she couldn't seem to stop.
Holtzmann sat at her work station, absentmindedly toying with the ScrewU pendant around her neck. Erin felt slightly mesmerised by the repetitive motion of her hands. The sliding of slender fingers over the smooth metal. She shocked herself by thinking that those nimble fingers probably had driven many girls crazy. And there it was again, her pink tongue. Erin stared at Holtzmann's lower lip as her tongue darted out and licked it. Her lips were so ridiculously full. And they always looked kiss swollen, somehow. It had taken Erin a while to realize how beautiful Holtzmann was. She had been distracted by the colorful chaos surrounding her. But now, she thought about it almost every time she looked at her. She had no idea if Holtzmann really knew. The first time Erin had seen her with her hair down and no makeup, she had stared for so long Holtzmann had asked if something was wrong. No, nothing. I just can't take my eyes off you and I have no idea why that is. She had discovered that Holtzmann's eyebrows were blond without makeup. Almost the same color as her hair. And here she was, staring again.
"Is there... something on my face?"
Erin felt heat in her cheeks. She might have been blushing.
"Sorry. Just spacing out."
***
Holtzmann almost didn't say anything all day. Even Erin, who could be oblivious of things like that, caught her looking at her several times. She saw her in the reflection of a shiny metal surface, distractedly running the pad of her finger along her lower lip. Her forehead was scrunched up, like she was worried about something.
"Patty?"
"Mmm?"
"Is this a bad outfit for me? Did I spill coffee on myself or something?"
"Nah, you look awesome. Why do you ask?"
Erin wore shorts. It might be a little premature, spring wasn't fully there yet. She'd had it with winter and refused to bundle up anymore. But they were warm for shorts and besides, they're not the type of shorts meant for summer anyway, they’re too warm and too formal. She wore tights underneath, just in case.
"Holtz has kind of been staring at me, like something's wrong."
Patty laughed.
"Baby, there's nothing wrong."
"But…"
"Listen. You look really good in shorts, you have great legs. Holtzmann was probably just checking you out. She's sucker for the ladies, she can't help it. It's like with you and Kevin."
Erin felt almost offended, but she had to admit that it was a fair assessment. She tried to remember the last time she had ogled Kevin. Was it after saving New York? She realized she hadn't given him much thought at all, lately.
***
Holtzmann went out that night, she didn't say where. Erin stayed behind to do some reading and get some alone time. She used to love having time to herself and she hasn't had much of it lately. In the quiet fire station, she discovered that she might have lost her taste for it. She missed Holtzmann. It's not even ten when she started to feel annoyed. Where was she? Why wasn't she home yet? It's after midnight when she finally comes. Erin was tired and had almost given up and gone to bed. She smiled when she heard the familiar steps downstairs and went to meet her. When Holtzmann swore and knocked something over, Erin realized that she's drunk. Much drunker than Erin has ever seen her.
Holtzmann caught her by surprise when she wrapped her arms around her neck. She smiled a drunken, euphoric smile.
"Babe."
"Hi, Holtz. Good night?"
Holtzmann buried her face in the crook of her neck, pushed her nose against Erin and inhaled. She made a contented noise. She looked up at her and while it was obvious that she's seeing at least one of Erin, if not two, Erin got distracted by her beautiful blue eyes.
"What if it's this world?"
Erin didn't understand.
"This world what?"
"What if… We were married in this world? What if this is the world where that happens?"
Erin froze. She kicked herself mentally for leading Holtzmann on by going along with all the banter about being married. She didn't want to hurt Holtzmann's feelings. She didn't want to risk ruining the dynamics of the group. She panicked.
"Funny, Holtzmann. Really funny."
Her laughed sounded so forced she cringed. She smiled stiffly, way too widely to seem real.
"Let's get you to bed, Jillian."
She couldn't look at Holtzmann. She didn't want to know if there was hurt on her face. She hated when Holtzmann was sad. But she was straight. And they were working together. And she was going to pretend that this had never happened.
Holtzmann pushed her hand away, gently.
"Sorry. I'm… Sorry. Gonna go to bed."
When Erin reached out for her, she took a step back.
"Thanks, but I'm good."
Holtzmann walked toward her room in a perfectly straight line. Erin seemed to have sobered her up better than black coffee.
***
The next morning, she stiffened as she heard Holtzmann coming toward the kitchen and forced her face into a cheerful mask. She heard Holtzmann take a deep breath right behind her, before saying anything.
"I'm sorry. About yesterday."
"That's OK. You were drunk."
Erin hated the brittle cheerfulness of her voice. Holtzmann must hear it too.