It was Howard who realised that Sheldon and Penny had become 'neighbours'.
It was when Penny came over and asked for a cup of sugar. Sheldon stood, moving to the kitchen, asking if that was white, brown, caster, or icing sugar that she wanted? He then proceeded to rattle off the pros and cons of each variety. Howard sat on the couch and realised as he watched that the two had become more than just people who lived across the hall from each other. He observed as they made small talk, Sheldon painstakingly measuring out the sugar, and Penny asking how his latest experiment was going. He replied and handed her the cup, careful not to spill any. She smiled and thanked him, and he nodded politely before walking her to the door, wishing her well with her baking or whatever it was she was doing. She smiled again and said that she'd bring over some cupcakes for them later. He said thank you in advance and ended the exchange with a polite smile.
Howard thought that it was a very good thing that they had adjusted to each other so well. Though they still bickered, it was nice to know that they were at least capable of being good neighbours to one another.
It was Raj who realised that Sheldon and Penny had become 'friends'.
It came as a shock to him, when Sheldon called Penny's name and not his own. He felt a strange tug of jealousy as Penny took her seat on the couch beside Sheldon and he looked at the two of them, assessing the situation. He hadn't realised it until now, but they had been spending much more time together and had been arguing less. There was still the occasional bicker, but nothing as bad as when Penny first began to hang around with them. Raj decided that they must have gotten used to each others tics and quirks, and he found that he was slightly put out by this observation. He had known Sheldon for quite a few years now and it was vaguely… sobering to realise that he had been 'replaced' by the blonde neighbour without a PHD.
Although he was soon back in, having his Thai with the rest of the group, Raj didn't forget that Sheldon had picked Penny's friendship over his – and looking at the way the two interacted, he realised he was surprised he hadn't noticed it before. The two had become really quite friendly and though he was still slightly hurt, Raj decided he couldn't really hold it against them. After all – friends don't hold grudges.
It was Penny who realised that she and Sheldon had become 'best friends'.
They were sitting next to each other on her couch, laptops out and gamer lingo flying as he helped her with a quest. Penny had gotten over her addiction to Age of Conan with Sheldon's aid long ago, but she still played – but only on Tuesday evenings and only with the physicist by her side, ready to help in case she lapsed back into her old habits (he was also great against goblins). Sheldon had been staring intently at his screen for awhile now as he made his way to a new, extremely magical treasure, when Penny's cry of frustration and shock made him flick his gaze to her laptop. She was being attacked by a group of orcs and without thinking; he abandoned his quest and was soon by her side, slashing at the enemy. When the orcs were all dead, and Queen Penelope had made her way safely through the forest trail (thanks to her guide, Sheldor) Penny paused her game, and turned to look at Sheldon, who had done the same.
"You abandoned your quest to come to my aid – why?" she asked, and he quirked an eyebrow.
"Is that not what friends do? Help one another?"
Penny smiled and found herself giving him an awkward, one armed hug.
"It's what best friends do" she said, and Sheldon paused, looking at the girl who had one arm around his shoulders.
"Am I to understand that our relationship paradigm has progressed to the stage of 'Best Friends?" he asked, and Penny rolled her eyes at his typical way of phrasing 'since when have we been BFFs?'
"I would say so. You're the only one of my friends that knows most of my secrets, and I imagine I know all of yours…"
"Considering I cannot keep one" he added, and she grinned.
"Well, not from me anyway. But yes. I'd say that you're probably my best friend."
"Is that a bad thing?"
He shook his head hurriedly, and gave her a smile before lapsing back into his worried expression.
"Sheldon, what's wrong? Don't you want to be my best friend?"
"Of course I want to be your best friend Penny – It's just…" he paused and she gave him a questioning look.
"I'm going to have to inform Leonard that he's out."
It was Sheldon who realised that he and Penny were 'dating'.
It was a Thursday night and the group of friends were playing boggle (English, so that Penny could be included) when a certain word came up at the top of Sheldon's list.
He knew what it entailed, certainly…though not exactly from experience. So, he decided to check the dictionary term.
As he went over the definition, Sheldon felt a thought creeping around the back of his mind. He paused in his reading; whenever he got this feeling, it was best just to let it slowly dawn, rather than forc-
His blue eyes widened.
He quickly marked the page and then slammed the dictionary shut, stood up, grabbed Penny's arm and dragged her out into the hall, ignoring the curious protests from both her and the others.
Sheldon shut the door behind them, and turned to his confused friend. "Penny, do you understand the definition of 'dating'?" He asked, thrusting the dictionary with its marked page into her hands. "Because I find myself unsure about whether or not…" He trailed off into silence, suddenly uncomfortably aware of the tanned blonde before him.
Penny was reading the page, and her green eyes suddenly snapped up to his, a shocked look on her face.
"Oh my God."
Sheldon nodded; glad he wouldn't have to lay it all out for her.
"Exactly. Penny we are, for all intents and purposes… dating."
Penny looked from the dictionary in hand to Sheldon, trying to process what he had said.
Dating? Them? It couldn't be true…They were complete opposites! They were neighbours; they were friends – best friends – they were…
Penny pulled herself back to what it was Sheldon was saying as he paced nervously in front of her.
"-but I am unsure as to how, when or why. Our relationship paradigm seems to have progressed unawares, whether or not we like it or wanted it-"
"Do you want this?" Penny found herself asking and Sheldon turned from his pacing to look at her.
"Do you… want… to be dating me?"
Sheldon began his pacing again, occasionally glancing at her as his cheeks flushed pink.
"I…I don't know. Certainly, there is attraction there; you are the perfect definition of perceived beauty in western society, and I think that it would be nigh impossible to find someone who doesn't recognise the splendour you possess… I find your company to be more than tolerable; increasingly I find myself seeking out your companionship, even taking into account the strange heart palpitations and breathing difficulties that I experience when you are near. I respect you; despite your lack of any PhDs or Masters, you are clearly intelligent and can hold your own against me. You even, admittedly, surpass me in a select few areas, such as social protocol and pop culture."
Penny sighed; she should have known he wouldn't be one for a short answer to a (seemly) simple question. She moved to the wall across from the elevator and sat down, watching as Sheldon continued his deliberating.
"-and even though you are constantly irritating me, no doubt on purpose, I often find that I cannot make myself give you a strike, or banish you from the premises… and it aggravates me – You aggravate me!" he said in sudden clarity, looking down at her. "You are annoying, yet I enjoy your company. You dropped out of University, yet you manage to hold your own intellectually against me. You are absolutely stunning, and yet I know you are, as I believe the colloquial saying goes 'way out of my league' – it doesn't matter that I want to be dating you, because there is such a low chance of it happening it might as well be counted as an impossibility!" he ended in what he thought to be a logical tone of voice, sitting down beside Penny on the floor.
She stares at him, briefly wondering when he would mention the number of germs they were exposed to in their current position. Then her mind grasped at what Sheldon had said.
He thinks she is beautiful.
He thinks she is smart.
He enjoys her company.
He wants to be dating her.
She takes a moment to process this thought, then examines the man next to her. He is staring straight ahead, blushing slightly at his outburst. His blue eyes are serious and his brown hair is slightly mussed because of the number of times he's run his hand through it. Penny's eyes widened as four realisations hit her at once.
She knows he is cute – handsome even.
She knows he is definitely smart – but he needs her to explain certain things.
She loves spending time with him –no matter what they were doing.
She wants to be dating him .
So (big ol' five that she is) with one hand she turns his face to look at her. One hand cups his cheek and he leans into the touch, even as his curious dark blue eyes meet her own. She leans forward slowly, her lips meeting his in a slow, gentle, chaste kiss. She pulls away and smiles at him.
"Sheldon haven't I told you to always believe in the impossible?"
He shrugged meekly, his cheeks flushing again.
"I am a scientist Penny. I cannot believe in impossibilities without sound evidence, which after evaluation can be either proved or disproved as fact."
She rolled her eyes with a smirk and lowered her lips to his again. When she pulls away, they are breathing heavily. His eyes are closed and Penny smirks.
"That enough evidence for you?" she asks in a sultry voice and he doesn't reply, too dazed. She gives a quiet laugh, and sits up, pulling him to stand beside her.
"I think I'll leave you to evaluate the evidence. Let me know when you're ready with your theory."
She goes to turn away to her apartment, but a tug on her wrist and she is back in his arms and he is kissing her hungrily. His mouth is devouring hers, biting and sucking and their tongues are dancing and his hands are on her hips and Penny feels as though she will die if they stop or if they continue… either way she is doomed and she decides that this isn't a bad way to go.
She can watch over everyone from heaven. Hell. Wherever it is she's going.
(Probably hell, based on what she's thinking of doing to the Physicist with his hands smoothing the skin on her hips and lower back…)
He pulls away and she realises his long arms are the only things holding her up. He leans his head down, his breath warm as it plays about her neck, causing her own breath to catch slightly as he whispers in her ear…
"Penny…What I feel for you is nothing short of the most obvious, startling, wonderful reality I have ever come across. We are not a theory. We are fact."
Her green eyes crinkle at the edges as her smiling lips find his once again.
It was Leonard who realised that Sheldon and Penny were going to get married.
The two have been together for just over a year now, and they are both happy, he knows. They haven't had an argument since Penny accidentally smudged an important equation on Sheldon's whiteboard – and seeing as it was because he had pushed her up against it (or so Leonard had heard her yell across the hallway) it was hardly her fault at all. Since then, they hadn't fought at all, and this was why Leonard found Sheldon's current behaviour to be so strange. He had been avoiding Penny for the last few days and had barely left his room, except for work and bathroom trips. Their anniversary was this coming Friday and Leonard couldn't figure out why Sheldon was acting the way he was – so he decided to interrogate his best friend.
He knocked on Sheldon's door, only to receive a 'please do not disturb me Leonard' and then silence. Leonard ignored Sheldon's request and opened the door. He was sitting on his bed and at Leonard's entrance gave a high pitched yelp, shoving something under his pillow.
But Leonard had seen what he had been holding.
He had seen the almost scared reverence on Sheldon's face as he looked at the blue velvet box in his hand.
He also saw the apprehension that was shining in his friend's uneasy blue eyes as he looked at him guiltily.
Leonard took a deep breathe and slowly let it go.
Let Penny go, once and for all.
The silence was broken by Sheldon standing up, stuttering.
"Leonard I… I can expl-"
"Explain? There's nothing to explain."
Sheldon's face fell, and Leonard took a step forward.
"You were just about to ask me to be your best man, weren't you?" he asked, cocking an eyebrow playfully.
Sheldon's shoulders dropped from their previous tense position as a cautious smile crept onto his face.
"Really Leonard – I didn't think I needed to ask. You are the logical choice after all."
The two friends eyes met and they smiled in mutual understanding.
Sheldon was getting married.
And Leonard couldn't be happier for him.