"Where did this letter come from?" Leonard asked, waving the piece of mail in the air. "It's Penny's."

"The mailman accidentally put it in our box," Sheldon replied.

"Why is it open?"

"I didn't realize it was Penny's before I opened it."

Leonard hesitated. "Did you read it?"

"That was how I realized it was Penny's."

"What does it say?"

"If you really want to know, read it yourself."

"Isn't that kind of like snooping?"

"How is it not snooping for me to read it but snooping for you to read it?"

"You didn't realize it was someone else's. I would know it's not mine before reading it."

Sheldon paused to consider this. "Penny's behind on the rent."

"She is?"

"Three months."

"Do you think we should help her out?"

"Nope."

"We could just give the landlord a little extra and tell him it's for Penny; she'd never even have to know…"

"Leonard, I don't think she's not going to sleep with you for rent money."

-x-x-

It was a bright and sunny day in Pasadena, California. The first day of spring, to be exact. Any normal, fun-loving person, devoid of prior engagements, would have been outside on a day such as that. And most people were.

Children were flying kites in the park. Many people were out surfing. Bikinied girls were lying on the beach, rich movie stars were sitting out by their pools…

Not the residents of apartment 4A, though. No, as usual, they were huddled over their computers at their individual desks, inputting calculations, scribbling down unintelligible equations… normal smart people stuff. But they were definitely not getting anywhere near The Outside.

They had been working in silent deliberation like this for some time when there came a knock at their door. Leonard Hofstadter immediately leapt to his feet, hoping it would be their neighbor, home from her usual errands a little early. Sheldon Cooper glanced towards the door with a vague air of indifference, hoping it was someone who would go away quickly.

"Hey, guys!" a pretty brunette drawled, breezing into the living room with a comfortable familiarity that made Sheldon shiver. She pulled her pink baseball cap off her head, letting her dark brown hair fall just to her shoulders.

"Oh, that's right, I forgot I called you," Leonard observed, downtrodden.

"You were expecting someone else?" she asked, raising her eyebrows.

"He was hoping you were Penny," Sheldon stated.

"Oh…" The brunette grinned. "Your Girl Next Door."

"Technically, her door is across from ours, and, even then, the sides don't match up evenly."

"Sheldon, shut up," she commanded.

The tall man's cheeks grew hot. "How long are you going to be here, Ellie?"

"As long as it takes to fix your sink, Sheldon, which you're too cheap to pay a plumber to do, and too lazy to do yourself." She stuck her tongue out at him.

Instead of quieting him, like this remark would have done to most people, he only became more riled up. "I have more important things to do with my time than manual labor."

"Well… you're a jerk! I do nice things for you all the time and Leonard's the only one who thanks me!" Ellie whined.

"He's your brother; he has to!"

"Children, please!" Leonard interjected, stepping between the two before their fight came to physical blows – though their brawls never did, it was better safe than sorry. "Sheldon, why don't you leave, like you usually do?"

"I have work to do! Why should I have to leave? I live here. She should leave."

"Would you like the kitchen sink to work?"

Sheldon cast a glance over towards it. "That would be better than the alternative, yes."

"Then go to Koothrappali's and do your work there. He won't mind. Just take your laptop and your board and take the bus-"

"The bus?!" Sheldon shrieked, as only Sheldon could.

"Okay, fine! Take my car! Just get out of here, please!"

-x-x-

Leonard crouched down beside the sink, considering how to best approach the touchy subject he had actually asked his sister over to talk to her about.

"Hey, Ellie?"

"Yeah?" she asked tentatively, recognizing the tone of his voice. It was the "I'm going to ask you a favor" voice.

"Are you still looking for an apartment?"

"Um, well… my friend has someone looking at a room in her apartment already, but she said if that falls through I can stay with her… that's basically the best lead I've gotten so far."

"How would you, um… how would you like to live in this building?"

"Lenny, I can't afford your rent."

"Could you not call me Lenny, please?" he asked. "Anyway, the rent wouldn't be as high as what Sheldon and I pay. One of our neighbors has a slightly smaller apartment, and she can't quite make rent, so I think she might be looking for a roommate…"

"What neighbor?" Ellie asked, pulling herself out from underneath the cabinet, but not before hitting her forehead on the edge. "Ow."

"Well… she lives on this floor…"

"You want me to move in with Penny!" the young woman guffawed, shaking her head and sliding back under the cabinet. "I've never even met her."

"She's nice."

"I'm sure she is, otherwise you wouldn't like her so much. But I don't know her."

"You guys would get along really well. She's messy, too."

Ellie chuckled. "Oh, well, if that's the case," she stated sarcastically.

"Just think about it, okay?" he begged. "She doesn't have the money."

His sister sighed. "Okay, fine." He sat beside the sink for some time while she grunted, trying to turn a bolt. Finally, the silence became unbearable.

"So… Sheldon seems less anal than usual," Ellie commented, her legs sticking out from underneath the sink.

"Yeah, you know, I actually think he's getting better."

"Wouldn't it be really funny if he got really mad one day and just turned into the Hulk? I could totally see that happening with him. He's got the veins in his forehead and everything."

There was a knock on the door; Leonard rose from his crouch to answer it. "In Sheldon's defense, Ellie, you do goad him on."

"I'm not denying it," she replied as he opened the door.

"Penny!" Leonard exclaimed excitedly, and perhaps a little too loudly, since the blonde winced visibly. "Sorry, uh… we were doing sound experimentation at the lab and now my hearing's a little off."

Ellie snickered and banged something against a pipe, causing a loud, metal clang.

"What was that?" Penny asked, furrowing her eyebrows and glancing around.

"Oh, that's just my sister, Ellie," Leonard explained, shrugging. "She's fixing the pipes under our sink."

"Is she a plumber?"

Leonard laughed. "No. She's just good at that kind of thing. You should have seen how quickly she put together our new entertainment center. It was like watching a master at work."

"Oh." Penny smiled. "I never knew you had a sister."

"Wow, that's a surprise," the young woman stated sardonically from beneath the cabinetry, her voice muffled by her immersion under the sink, and the distance.

"Oh!" Penny hadn't realized she could hear them talking. "Hi! I'm Penny, from next door."

"Hey, Penny From Next Door!" Leonard's sister called back, waving a grimy hand in the air behind the island in the middle of the kitchen. It was the only part of Ellie that Penny could see, aside from a pair of powder blue Converse. "I'd come out, but I'm not presentable."

"Oh, that's okay," Penny laughed. She imagined Ellie to be a female version of Leonard, albeit younger and maybe with a few more social graces. "I'm sure I'll get to see you later."

"Yeah, yeah! Come over for dinner tonight!" Her hand waved in the air more frantically now. "I'm making cupcakes and chili!"

"It's a 'C' day for her, I guess," Leonard explained. Apparently he thought it was funny.

"Oh, gosh, guys, I'd love to come, but I have work tonight. Sorry. Definitely another night, though." The blonde smiled apologetically. "Raincheck." She glanced at the clock on the wall. "Speaking of work, I have to shower so I can get there."

"We'll have leftovers," Ellie stated. "Want me to bring you some?"

Penny smiled. "Yeah, that'd be nice."

"Alright, cool! Nice to meet you!" Ellie waved her hand once more.

"Bye!" Penny smiled and paused in the door. "Bye, Leonard."

"See you later, Penny," he replied, suddenly shy, watching as she crossed the hall to her apartment, and then closing the door. A few minutes later, Ellie popped out from behind the island, her hair pulled back into a sloppy ponytail and grime from the pipes smeared over her face.

"She seemed nice," the younger sibling commented, passing the wrench to her brother and resting her gloved hands on her hips.

"Yeah," he agreed. "She is." Ellie watched him closely, a knowing smile on her face. "What? Why are you looking at me like that?" Leonard asked defensively.

"Nothing. You just seem… happier." She placed her hand on his shoulder and kissed him on the cheek. "I have to go to the grocery store. Is Sheldon eating with us tonight?"

Leonard pretended to think. "Um… I think his exact words were 'And eat that toxic waste your child of a sister decides to cook up in her Easy Bake Oven? No thank you.'"

Ellie smiled. "That sounds like Sheldon. If you see him, tell him I love him too."

-x-x-

Penny hadn't been home from work for ten minutes before someone knocked on her door. She peeled herself away from the TV, ran her fingers through her hair, and opened the door, knowing it to be Ellie. She was just surprised Ellie looked like that.

Ellie was a tall-ish thin brunette with big eyes and a radiant smile. Despite what her Converse had suggested (which, basically, was that she was just as bland a dresser as Leonard) she was dressed well in a purple tube top and straight-legged jeans. She had a Tupperware container full of chili in her hands. The two stood and stared at each other for a minute, before Ellie held out the Tupperware container.

"Hey, Penny. I'm Ellie. We met earlier today?"

"Yeah, yeah. Right." Penny smiled.

"I brought you some chili. It's my dad's recipe. I hope you like it a little spicy."

"Thanks." The blonde grinned and accepted the container. "Do you want to come in for a while?"

"Oh, yeah. Sure." She sat down on the couch while Penny put the chili in her fridge.

"So…" Penny smiled awkwardly, sitting on the chair adjacent to Ellie's couch. "You're Leonard's sister."

"Yep."

"How far apart are you guys?"

"Seven years. Leonard's thirty, and I'm twenty-three. And we also have a sister, Amelia, who's still in college. She's nineteen."

"Wow. So… she's eleven years younger than Leonard."

"Yep…" Ellie nodded. "Basically… pretty much." Their awkward silence was empty, devoid of anything to actually say to the other one.

"I guess I didn't really expect you to be like… this," Penny stated, gesturing towards her clothes. "I mean, the way Leonard talks about you…"

"You were expecting me to be a geek, too?" Ellie inferred, smiling. Penny bit her bottom lip, unsure if Ellie was joking, serious, or trying to get her to say something rude. "Yeah, I get that a lot. I'm kind of a geek too, but more of a closet geek. Out of my three siblings, I'm definitely the most normal, although that's not saying much."

"Yeah, I guess I didn't want to just come out and say… geek…"

"Oh, it's okay. Leonard likes being a geek. Mostly."

"And Sheldon?"

The brunette scoffed and rolled her eyes. "It's the only role in society where he can be a jerk to people and get away with it."

Penny smiled. "I take it you don't like Sheldon."

"Do you?"

She paused. "Not really, actually. I guess I never really thought about it until now."

"You know those people who are really good friends, even though they fight all the time? Like, its just part of their social dynamic, and it works for them?"

Penny rolled her eyes up to the ceiling thoughtfully. "I… guess so."

"Sheldon and I aren't like that. He just hates me."

"He hates most people, I think," Penny pointed out.

"This is true." The girls giggled. "So… Leonard kinda told me you were looking for a roommate."

"Oh… he did, did he?" Penny suppressed a frown. "Look, he's a nice guy, but he doesn't have to get his sister to come and pretend she needs a roommate just because I'm a little strapped for cash right now…"

"No, that's not it. I mean, that's why he came to me, but that's not why I came. Believe me, if it was just for you, I wouldn't do it. No offense, you're a nice person, but I didn't know you. But I need a place to stay too. My apartment's being torn down in a couple months."

"Oh, wow. Really?" Ellie nodded somberly. "That sucks. How much warning did they give you?"

"I just found out last week."

"Oh, God. Well, yeah, then, in that case, I definitely need a roommate. I mean, I'm obviously not the world's best housekeeper or anything, but I'm clean… I just don't organize… anything. And I can't really cook, either."

"That's okay. That's what TV dinners are for!" The girls laughed. "I mean, I'm an okay cook. I'm just, you know, usually busy with other stuff… I write, and I'm an actress, and I work at a restaurant."

"Ohmigod! Me too!" Penny exclaimed. "I work at the Cheesecake Factory, and I'm trying to become an actress! And I'm writing a screenplay!"

"Cool!" Ellie grinned. "When we're famous, we'll be like Clark and Michael, or something!"

"Ohmigod! You watch them too?!"

Ellie rolled her eyes. "Yes. Only, like, every day!"

"This is so perfect!" Penny exclaimed happily. "You're going to be the best roommate ever!"

-x-x-

The two young women stumbled haphazardly into Leonard and Sheldon's apartment, giggling profusely. While they had been deciding to become roommate, Raj and Wolowitz had arrived, and the men had begun playing some unidentifiable video game.

"Guess what?" Ellie asked, falling onto the couching beside Sheldon heavily.

He didn't take his eyes off the TV, nor did his fingers slow down, for a moment, when he responded to her. "You're moving out of the country!" he declared cheerfully.

"Even better," the brunette stated.

"She's moving in with me!" Penny squealed, clapping giddily. "I'm so excited! The last roommate I had was this weird goth chick who painted her walls black, but the super got really mad and made her paint them-"

"No one cares, Penny," Sheldon retorted, actually pausing the video game. Amidst groans from the other men, he turned to Ellie. "You've actually moving in with her?"

"Yeah! We're gonna be neighbors, Sheldon!" she exclaimed, wrapping her arms around him. He stiffened awkwardly, not sure if it was Ellie's hug or a woman's physical contact in general that was making him so uncomfortable. He was willing to bet it was because of Ellie specifically; no matter what she did, she always rubbed him the wrong way.

"Leonard?"

"Yes, Sheldon?" Leonard asked exasperatedly, knowing what vein the coming question was in.

"We better start going to those warehouse stores for our Tums."