This started out as a drabble. It got a tad longer. It takes place at some point – either past or future – when Leonard/Penny are an established couple. Enjoy!
DISCLAIMER: I don't own anything. If I did, L/P shippers would probably be a lot happier right now.
Leonard loves it when Penny thinks.
When he says that to her, she appears to take it as an insult. "Why, because me thinking is such a rare event you're so shocked by it? 'Ooh look, she's thinking! Stop the presses'!"
He's not surprised that that is her reaction to his comment. But he doesn't mean it like that. And he knows that she knows it. Because they've had this conversation before.
He doesn't love when she thinks. She does that all the time. He loves it when she embraces his way of thinking, and he sees in her a glimmer wonder that drives all the great minds forward. He loves when she wants him to share his world with her.
He loves it when she puts down the nail polish and switches off America's Next Top Model and turns down the Keith Urban and asks "what's the double slit experiment?" because she'd heard him mention it to the punch line of a joke that she laughed at, but really didn't understand. And when he explains it to her, he can see her watching him, staring, unblinking, her eyebrows twitching slightly as she takes it all in. Then she slowly nods, repeating what she figures is the most important part of his explanation slowly back to herself, so she can apply it in conversation later.
He loves it when he's explaining to her about an experiment he's done and she gets confused. He loves when her frustration over not knowing drives her almost to tears. He doesn't love that she's upset, far from it, but he loves that she cares enough to get that upset. She knows that he's not with her because she can rattle off Newton's Laws of Motion, because she can't – although she's got the force equals mass times acceleration thing down now. But still, even though she knows that he'll have her whether she has an interest in what he does or not, she wants to learn. She wants to bend over a notebook again and stand behind him while he works things out on his board. She surprises him at his work, throws on a pair of goggles, and watches him use lasers to melt various pieces of plastic. She volunteered an old Barbie doll for the mission once, but he wouldn't melt a female. She rolls her eyes again, and asks to be the one to use the laser. He should say no, it's for employees of the university only, but he's never seen that enthusiasm in the eyes of a fellow scientist, so he stands next to her as she uses it, proud that this is his girlfriend rendering the one – legged Hulk into a shapeless lump of green plastic.
He loves watching her roll her eyes when he starts making analogies between their lives and scientists, or science fiction literature and movies, because right after the eye roll the side of her mouth always curves slightly upward in amusement. She complains about his nerdiness sometimes, she has to, but then she cuddles up to him anyway, accepting him for what he is. And then she whispers in his ear that he's better looking than Mark Harmon. And he reminds her that it's Mark Hamill that plays Luke Skywalker.
"Right," she says, her mouth smiling, her eyes disappointed that she got it wrong, and her eyebrows and forehead twitching again, ever so slightly, desperately trying to recall when and where they were when he told her that. "Hamill." She repeats. "Hamill." Disappointment takes over her face, her mouth falling toward the low point on her face, lips collapsing out of the smile.
At this point, Leonard puts his arms around her and kisses her cheek. "But I'm cuter than Mark Harmon, too?"
Seeing he's not judging her for getting the name wrong, Penny grins and touches his chin with her finger. "Of course," she says, and they smile at each other. And he loves that moment.
He loves when all of this happens.
But what he loves the most is that even though there are dozens of different ways that people's brains operate, even though all of them are good and useful and even though Penny's brain is not the same type that his is, she'll still ask him questions, about his work, his comic books, or his H.G. Wells novel, and when he answers she'll still look at him, staring, unblinking, eyebrows twitching ever so slightly as she takes it all in.
And the light has begun to come into her eyes. That fever, that longing for knowledge that drives all great scientists. Her light is not the same; she will never make a life changing discovery in physics, but she's become so eager, so enthusiastic about everything that he loves, and she wants to know it all, and think about it all, because it's important to him, and it makes him who he is, and she wants to know all about it because if it's a part of him, then she can't get enough of it.
His world is so important to him, and for her to even try to understand it…it's enough. He wants to share it with her, and she lets him. Hell, she asks him to.
And he loves it.
Of course, it takes many of these conversations before both of them know all of this. But by the fifth time that he says "I just love it when you think," and she turns on him and says "Why, because me thinking is such a rare event you're so shocked by it? 'Ooh look, she's thinking! Stop the presses'!" he knows that she isn't really mad. She just wants him to tell her again how much he loves it when she looks at him, staring, unblinking, eyebrows twitching ever so slightly as she takes it all in.