Leonard, Raj and Howard all looked up when Sheldon pulled out a seat beside his roommate and sat down at their usual lunch table, and Leonard greeted him with a friendly smile. Sheldon's head nodded slightly in response, before fixing Raj and Howard with a penetrating stare. 'Will you two be joining Leonard and I for dinner at The Cheesecake Factory or will you be working on your friendship again?'

'We'll be there, dude,' Raj replied as he picked up his fork. 'I'm in the mood for cheesecake anyway.'

'That's not all you're in the mood for,' Leonard snickered, earning identical glares from the Indian/Jew duo. Sheldon's forehead crinkled in confusion as he considered the shorter man's statement. What else would Raj be in the mood for? Paintball?

'Drop it Leonard,' Howard hissed across the table, his glare never wavering. 'Not here, okay?'

'I told you we shouldn't have told him,' Raj pouted quietly. 'Now we're never going to hear the end of it.'

'You're the one who brought up the idea of telling him and talked me into it,' Howard argued, frowning at the man beside him. 'But you freaked out last second and I had to talk you into it.'

Raj decided not to give that statement a response and started to attack his lunch again, not noticing Leonard's amused look and Sheldon's confused stare. As Leonard contemplated how the pair acted much like an old married couple, Sheldon began to realise something was going on that he was unaware of. He debated whether to just ask, but judging from Raj's little speech on how Leonard shouldn't know, he doubted they would tell him. Maybe he could ask Leonard when they were alone if he couldn't figure it out. As he was mulling it over, a short figure stepped up beside the table, leaned over, planted her hand on the table and fixed her stare onto Howard and Raj.

'I think congratulations are in order,' Leslie smirked at them, before acknoledging the other two's presence with a, 'Hey Leonard, hey Dumbass.'

Before Sheldon could sputter out a horribly concocted comeback, Howard reached out and gripped the sleeve of Leslie's sweater, a look of panic on his and Raj's face. 'How the hell do you know? No one is supposed to know!' he suddenly looked at Leonard, his eyes narrowing. 'You told!'

Leslie freed her sleeve with a look of amusement. 'I saw you two, actually, late last night before you left for home.' She grinned and patted their shoulders. 'I hope it works out for you.'

'I don't suppose anybody is going to enlighten me on what that was about?' Sheldon asked disdainfully as she departed, using one of his many napkins to wipe the spot on the table where her hand had rested. Raj and Howard both shook their heads, and hurried their way through their lunch. Leonard laughed and clapped Sheldon on the shoulder.

'Not a chance, buddy.'

Sheldon huffed and took a sip from his soda can, his curiosity about Raj and Howard taking a back burner as he marvelled at the fact he was so tolerant towards being touched now. Before he had met Leonard, he had not allowed anyone but close family to touch him, and even then reluctantly. And now he allowed people to hug him, to touch his shoulder, even to fall asleep on him after a particularly stressful day. Granted, he only allowed Leonard to do such things, but it was still progress, right?

xoxo

Sheldon first began to realise the truth at dinner when Penny had arrived to take their orders and no bad pick up lines escaped Howard's mouth. They ordered their usual plates and chatted about Lord of the Rings as they waited, because apparently Raj had just re-watched the movies. Sheldon watched intensely as Raj cracked a joke and Howard laughed, and then patted the Indian's wrist in apparent appreciation for the joke. But his hand lingered a few seconds longer than needed and his thumb gently rubbed Raj's wrist before he removed it. When they looked at each other and smiled, Sheldon noted their eyes were dilated, indicating attraction.

Penny brought their orders and departed, and they started eating. Sheldon began to add up all the things that hadn't made sense and came to a shocking conclusion. He wondered if he should bring it up, then decided it would be rude to let them go around thinking he didn't know, when in fact he did. 'So,' he ventured, and they both looked at him. 'When did you two start dating?'

Raj began to choke on his cheesecake and Howard spluttered incoherently. Leonard looked at him with a slight smile, appreciating that Sheldon had actually worked it out when he was horrible at social conventions. As Howard hit Raj on the back, he glared at Leonard. 'You told?'

'No!' Leonard frowned at him, then at Raj who had just regained control of himself. 'I didn't tell anyone. You guys know I would never do something like that.'

Sheldon noted Leonard's distressed look and stared at Howard. 'He didn't tell me. If there's one good thing about Leonard its his ability to keep secrets.' In fact, that was something Sheldon envied him about. No one told Sheldon any secrets because he was horrible at keeping them. The shorter physicist smiled at him. 'I figured it out for myself. Spending time alone together, increased touching, not to mention your pupils dilate when you look at each other. I would say it's quite obvious.'

Howard scowled down at his plate but Raj, who thought it was useless to hide it since everyone at the table knew, reached out and took his boyfriend's hand gently, hoping he wouldn't get in a bad mood. Howard seemed embarrassed at the show of affection in front of their two friends but squeezed Raj's hand in response, making the darker man smile. Leonard watched them with an odd pang in his chest. It had been a while since he'd been in a relationship, not since he and Penny had last broken up. He kind of missed the intimacy, the love. In fact, the only person he was really affectionate towards was Sheldon, who generally felt uncomfortable when if Leonard went to far. But he did allow the Leonard to hug him, to lean his head on the taller man's shoulder and fall asleep after a bad day. As if sensing his thoughts, Sheldon turned to look at him, and Leonard smiled at him. For once, Sheldon actually smiled back.

'You two never answered my question,' Sheldon said some time later, after they had resumed eating. The couple seemed confused, so he elaborated, 'When did you two start dating?'

There was a slight pause as they looked at each other, and even without speaking they seemed to communicate. Apparently they decided Howard would tell the story, because he broke eye contact first and looked at Sheldon again. 'Well, the night we said we had to work late so couldn't go to HALO night? We actually went out to dinner. I kind of planned it to… seduce Raj, I guess. We went back to his apartment to watch a movie and next thing you know we wind up in bed.'

Both men were grinning in an embarrassed way, and Raj spoke up. 'So we decided to see where it would lead us and set a date, and that was the night we bailed out on dinner at the Thai food restaurant. It went well so… Here we are.'

At this, Howard smiled at him and they squeezed hands again, causing the odd pang in Leonard's chest to come back, and Sheldon to shift uncomfortably. The mention of the two in bed had given him mental images, and he was desperate to get it out of his head. In his mind he saw Raj lean down, trace a finger lightly over Howard's collarbone, an intake of breath, and then their lips met, melding together, bodies entwining and- Sheldon closed his eyes, trying to force it out of his head, when a sudden thought struck him. What would it be like to kiss a man? Would it be similar to kissing a woman? It seemed like it would be the same, if you just let go. He couldn't really ask Raj or Howard, not without gaining more, and possibly worse, mental images. Maybe he could ask Leonard? But then again, he didn't think the shorter physicist had kissed another man…

As Sheldon mulled it over, the four men finished their dinner. Raj, Howard and Leonard chatted comfortably; not minding that Sheldon was pretty much ignoring them. They recognised when he was thinking deeply, and the Indian/Jew duo were secretly glad he'd stopped drilling them on their relationship.

As they were driving home, Leonard left Sheldon to his thoughts, who was staring intently out the window. Leonard glanced over at him every now and again, as he was so quiet the shorter man was worried he might stop breathing or something. Sheldon, who was aware of everything even as he was thinking, around him, noticed the glances and the corners of his lips raised slightly. It was nice to be worried about. They were nearly home when Sheldon decided on the next course of action. He knew himself better than anyone, so he knew he wouldn't be able to function properly if he didn't find an answer to his question. And he knew asking people would only create images and make him uncomfortable. So… he'd have to find out himself.

Sheldon sat down at his spot as soon as they entered the apartment, and he patted the space next to him. 'Leonard, come sit down. I have something I want to ask.' Leonard seemed confused at this turn of events; normally they'd both be getting ready for bed right now. But he sat down where his roommate had indicated without question. Sheldon paused for a moment, gathering his thoughts before speaking again. 'While watching Koothrappali and Wolowitz flaunt their new relationship status, I wondered what it would be like to kiss another man.'

'And you're asking me?' Leonard raised an eyebrow. 'I haven't kissed a man, Sheldon. I don't know.'

'I realise that your previous sexual encounters, limited as they may be, have all been with women,' the taller man acknowledged. 'However, that's not what I was getting at. I want to propose an experiment.'

'What kind of experiment?' Leonard asked slowly, a suspicious look on his face.

'Under the Roommate Agreement, section 56-a, it states that if I am unable to solve a problem on my own and need you, you will help me,' Sheldon said matter-of-factly. Leonard frowned in response, almost grasping what the man was about to ask. 'I am curious as to how kissing a man would differ to kissing a woman. Seeing as I cannot find this out on my own, I want you to help me.'

'You want me to kiss you?' Leonard exclaimed, shocked. 'What the hell, Sheldon! Why cant you just ask Raj or Howard to explain how it feels?'

'Unacceptable,' the other man responded coolly. 'I would not be able to do so without wanting to hit my head against the wall repeatedly afterwards.'

'Ask someone else to kiss you!'

'Also unacceptable,' Sheldon raised an eyebrow, noting Leonard's distressed demeanour. 'I dislike being touched by anyone other than yourself.'

'You haven't even kissed a woman,' Leonard snapped, crossing his arms. He felt almost trapped, as if Sheldon's reasoning was so good that he had to do it. As a result, his temper flared. He didn't have to do anything, even if it was under the Roommate Agreement.

'Contrary to popular belief, I have kissed a few women in my time, Leonard,' Sheldon argued.

'No, Sheldon,' Leonard growled. 'Just no.'

As the taller man launched into a full-scale argument to try and convince the shorter one, Leonard closed his eyes and tried to think, a difficult thing to do when Sheldon was rattling on in the background. The man had never even shown an interest in anything to do with kissing, why now? And why with him? Sure, they were more affectionate than they appeared, but Sheldon hated showing any affection in public. Leonard usually restricted their hugs to when they were alone and comfortable. Why would the man think Leonard had any interest in men? Its not like he was gay. He'd dated Penny, had sex with her, and Leslie for that matter. But… Leonard realised he wasn't all that opposed to the idea of kissing another man either. And although Sheldon was annoying and frustrating and obnoxious, deep down he was in fact caring and charmingly naïve when it came to anything social.

'…Furthermore, if you are worried about being questioned on your sexual preference, you do not have to tell anyone, or-'

'Sheldon,' Leonard interrupted, his voice scratchy with sudden nerves. 'If I do this, will you shut the hell up?'

There was a pause where Sheldon looked surprised, as if he hadn't really expected the other physicist to agree so readily. 'Naturally, Leonard. I believe it would be rather hard to speak if my lips were otherwise occupied.'

The shorter man took a breath, trying not to think about what he was about to do and failing miserably. His stomach jolted, and his heart rate increased as he slowly leaned forward and reached out to Sheldon. Leonard placed his hand on the back of the taller man's neck, drawing him down so he could reach his face. Their lips were close, and Leonard hovered there, drawing out the tension, and then he brushed his lips, very lightly, against Sheldon's, and then again and again. Their eyes were closed but the smaller man felt it with the other man drew in a tiny gasp, and just as he did, Leonard pressed their lips together hard, almost possessively, and the intensity of the kiss skyrocketed. Unexpectedly, Leonard felt sparks of attraction surface, and he realised he was enjoying the kiss. He was kissing Sheldon, and he liked it. He felt as if butterflies had taken residence in his stomach and he could barely hear over the pounding of his own heart. He felt himself grow semi-hard as he took a risk and slid his tongue along Sheldon's lower lip.

The other man shivered at the touch, but didn't protest, his mouth opening to allow access. Leonard gripped Sheldon harder, overcome with a sudden need to be closer, to take this further. Listening to the urge, he shifted without breaking the kiss and boldly straddled the other man's lap. He almost groaned when he felt Sheldon's hands hesitantly rest on his waist, and he took that as a cue to further the kiss. As Leonard flicked his tongue against the other physicist's, he shifted his weight and abruptly felt something move beneath him, something growing hard and… Oh God.

Sheldon felt the unbelievable attraction of the kiss change to panic as his arousal grew. He wasn't in control; he couldn't understand what was happening. He felt Leonard shift his hands to grip his shoulders firmly and the panic grew. He broke the kiss suddenly and turned his face away, his breathing erratic, his face flushed. 'Leonard, I'm uncomfortable.' His hands dropped from Leonard's waist to his sides.

The shorter man drew back, staring at Sheldon's face, but the man refused to meet his eyes. Disappointment replaced desire as he did so. The strange twisting in his stomach was a new feeling, normally he had only felt this way about Penny, about women, but the kiss had awakened something buried deep inside him and he saw Sheldon in a whole new perspective. The man's lips were fuller than usual, slightly bruised from the harsh kiss, and Leonard had to resist the urge to capture them again. 'I'm sorry.'

'I wish to retire to bed now,' Sheldon stated stiffly, unsure how he should be acting around his roommate now. Was it normal to be this nervous?

'Sure,' Leonard slid off him, his disappointment growing. He was such an idiot for pushing Sheldon so far. He should have taken it slow, allowed the man to get used to the sensation, but instead he had rushed into it, and now look what was happening. Sheldon was leaving for his bedroom without another word, leaving Leonard alone with these strange new feelings. As Sheldon's bedroom door clicked shut, Leonard leaned back against the couch with a groan. Why the hell was he suddenly so attracted to him? It was just a kiss. An experiment. He tried to picture Penny, imagining her soft lips against his, but instead of feeling aroused, he just felt hollow. Leonard swallowed and croaked out a soft, 'Oh God.'

Hey guys. Hope you enjoyed this chapter. It's rather difficult to write about Sheldon, he's such a complex character. I hope I didn't mess it up too bad.

Just as a warning, there will be sex in later chapters. I have never written sex between two men before so bear with me. Fingers crossed it won't be totally horrid.

I appreciate any feedback you have so feel free to review.