Disclaimer: I own nothing :(
Sheldon Cooper sat at his whiteboard trying to figure his latest problem when the phone rang. As usual Leonard answered it.
"Sheldon it's your mother" he said handing the phone to Sheldon.
"Mother?" he asked
"...She didn't...well where is she?...oh dear god...do whatever you want mother but I don't think praying will help...yes I will...okay bye"
"What's wrong?" asked Leonard
"Joy" muttered Sheldon
"are you trying to be sarcastic?" asked Leonard.
"No" just as he said that there was a knock at the door, well actually three knocks.
Knock, knock, knock
"Sheldon"
knock, knock, knock
"Sheldon"
knock, knock, knock
"Sheldon"
"Oh good lord she's here" said Sheldon
"Sheldon, what's going on?" asked Leonard going to answer the door.
"No Leonard" protested Sheldon a little too late, Leonard opened the door to a teenage girl.
"Hello Leonard, where's Sheldon?" she asked
"Um, there?" he said pointing to Sheldon. Sheldon was giving the girl a death glare.
"Sheldon, you don't look happy to see me? Haven't you missed me?" she asked
"Why aren't you home?" he demanded
"Mother's being unreasonable" she complained
"I doubt it" scoffed Sheldon
"No really, she would not let me build a radiation centre in the backyard" she complained
"Oh been there, done that" said Sheldon, Finally Leonard cut in.
"Sheldon who the heck is this?" he asked
"Joy" he said.
"Curse my name" she muttered
"What's wrong with Joy?" asked Leonard.
"Besides the obvious" added Sheldon.
"Well Shelly" she said causing Sheldon's eye to twitch "Joy is a name that will not give me any respect in science, honestly 'Joy' what was mother thinking"
"You can't be here" said Sheldon ignoring the rhetorical question he usually felt the need to answer.
"oh, no I am not going back don't you see that-" started Joy
"I'm sorry" interrupted Leonard "Maybe I was not clear, who is this"
"Don't talk about be like I'm not in the room" she said unhappily
"This is Joy, my sister" said Sheldon continuing to glare at her.
"Apparently I am like Sheldon but look like Missy" shrugged Joy.
"Yes, she is quite intelligent" Sheldon said with obviously discomfort.
"Quite? I am smarter than you and most likely your roommate here" said Joy, Leonard felt that this was a good time to leave.
"Where are you going?" asked Sheldon.
"To go get Penny, I can't deal with two Sheldons on my own" said Leonard, as Leonard left Howard and Rag walked in.
"Hey, Sheldon, so you ready for Halo-" said Howard then noticed the girl with brown hair and blue eyes.
"Who's this?" asked Howard
"Joy, my sister" cringed Sheldon
"Why must you always grimace when you mention me?" sighed Joy.
"Well hello there Joy" said Howard flirtatiously.
"I'm 15 Howard" Joy rolled her eyes
"Okay then" Howard backed off.
"Raj, you can talk to me I am not officially a woman" sad Joy. Raj, who had previously been silent, looked alarmed that she had known that.
"How does she-?" asked Howard
"Joy, is a computer hacker" said Sheldon flatly.
"That's only what I do in my spare time, I am really a physicist" smiled Joy
Penny and Leonard then walked in.
"Penny?" asked Howard
"I heard there was a 2nd Sheldon here" she said scared
"Yes, while that is highly improbable I suppose Sheldon and I share some similar characteristics" said Joy.
"Oh my god" said Penny.
"I know" said Leonard
Joy then decided to look around, she examined the apartment. She then walked over to Sheldon's spot and sat down.
"This is my spot" she declared
"Oh dear god" said Howard
"What the heck is so special about that spot?" exclaimed Penny, Joy and Sheldon looked at here oddly.
"Sheldon, do you always associate with people of such low intelligence?" asked Joy
"Excuse me?' asked Penny offended.
"Really, this spot clearly is close enough to the generator so in the winter I would not be to hot nor to cold in the summer by my calculations if I open windows there and there is will create a cross breeze and it is angled-" she was cut off by Sheldon.
"Joy they know I told them" said Sheldon
"Do they have by any chance have memory loss?' she asked
"That's it I'm out of here" Penny thew here hands up in air.
"Oh okay bye" said Leonard weakly
"Sheldon does Leonard happen to want to have coitus with her?' asked Joy not bothering to lower here voice "If so he is way out of his league, that relationship is doomed to fail"
"Oh look Sheldon's clone sees it too" said Howard
"Shut up" said Leonard
"Well I am going to go get settled in" she said standing up
"What?" said Sheldon startled
"Sheldon, I know you are not as smart as me but I thought I was quite clear, I will talk to you people later" she said and walked to Sheldon's room.
"Um, Sheldon?" asked Howard
"I know, she is just a conceited arrogant, annoying child" said Sheldon
"I wonder where she get's that from" said Raj
"Hey Sheldon, I used your toothbrush I hope that's okay" she said with a mischievous look on here face.
"Shoot me, find a gun and shoot me" Sheldon told Leonard.
A/N: well that's the first chapter, sorry if it OOC it's my first Big bang theory fan fiction please review! I will update regularly, and if you want it to become Penny Sheldon, I'll do that please let me know.