Kaylee smiled brightly and hummed softly to herself as she made her way through the cargo bay, heading to the infirmary to meet Simon. For the first time since she'd boarded the Firefly class transport ship as a crew member, they had touched down on a core planet and flown under the radar to a cute little seaside town where they could stay a while and relax. She felt pretty in her light pink, mid-thigh, strapless summer dress and the pink satin kitten heels she'd borrowed from Inara to match.

Rounding a corner, Kaylee skipped down the stairs into the common room and entered the infirmary, frowning when she realized Simon wasn’t there. Shrugging, she figured he was probably still getting ready for their outing and took a few more steps into the room.

Glancing around, she slowly stepped along, running her hand over the countertop and pondering the various sundries Simon had laid out. She didn't know what anything was, really, at least until she came upon something she recognized. Reaching out, Kaylee picked up Simon's stethoscope, twisting the tubing in her hands absentmindedly as she considered what she was holding. She'd watched Simon use it before and knew what it was for, but she'd never had the chance to try it out despite her nagging natural curiosity.

With the intention of trying the stethoscope out in mind, Kaylee threw a quick, cursory glance over her shoulder to make sure she wasn't being watched. She knew that the others had all left the ship already and that River had promised Mal she'd stay in the cockpit and watch over Serenity, but she couldn't help double checking anyway.

Once she was sure that no one was watching, Kaylee slipped the stethoscope on, adjusting it until the ear pieces seemed to fit most comfortably. Holding the chest piece of the stethoscope in one hand, she tapped gently against the diaphragm, surprised at just how loudly and clearly the instrument transmitted the sound.

Taking a deep breath and feeling a thrill go through her, Kaylee brought the diaphragm of the stethoscope to her chest, pressing it into place just over her left breast and listening intently. She smiled in awe and wonder as the sound of her heartbeat suddenly filled her ears. She had listened to Simon's heart before when she was lying with him and had her head on his chest, but that was completely different. With the stethoscope on, Kaylee found that it was like being surrounded by the sound, she felt like she could close her eyes and be transported right into the middle of a giant, beating heart.

Smiling softly, she continued to listen, marveling at her heartbeat. She had no idea how the heart did what it did or what caused it to change rate or rhythm, but she had no need for understanding. Just being able to hear her heart was an amazing experience and she found herself feeling excitement as it hummed through her veins, making her heart beat faster and faster as the emotion was driven up to a whole new level.

Kaylee shifted around as she kept the stethoscope still on her chest, turning until she backed up against the counter before hopping up onto it to sit comfortably. She breathed slowly, trying not to let the sound of the air filling her lungs overwhelm her heartbeat.

At that moment, Kaylee looked up, realizing she had lost track of time. Looking around, she noticed Simon leaning against the doorway to the infirmary, smiling softly with wonder in his eyes as he watched her. Wondering how long he'd been watching her, Kaylee gasped and fumbled the stethoscope, pulling it out of her ears and shoving it aside onto the counter. She jumped down onto her feet and ran her hands over the front of her dress, feeling her cheeks flush as she met Simon's gaze.

"Hi!" She squeaked nervously, feeling like a kid who'd been caught with their hand in the cookie jar. "So, ready to go?"

As she spoke, Simon approached her, feeling his heart leap with affection for her. She looked so youthful and innocent as she stood in a tense stance, having been caught red-handed with the stethoscope. She was absolutely beautiful and he was bent on making her feel just how much he loved her.

At the same time, Kaylee felt her heart pounding in her chest. The expression on Simon s face was unreadable and she didn't know whether he was angry with her or whether something else was amiss. He hadn't said anything, he'd just started walking towards her and it made her extremely anxious.

"Simon," she said, her breathing hitching, her voice unsteady. "I-I'm sorry, I shouldn'ta touched your stuff. I was just waiting for you..."

Just then, Simon was right there, his toes nudging hers as he coaxed her to take a step back, causing her to bump into the counter. She searched his face nervously as his features stayed non-descript, leaning against the counter and slipping back a bit so that she was once again seated on it with his legs bracketing hers as he reached the counter, too.

Kaylee wasn't sure what was going to happen, but she was admittedly surprised when Simon reached for the stethoscope she’d set aside, his gaze never deviating from hers. She swallowed thickly, sitting stock still as he slipped it on and brought the diaphragm up, resting it gently on her chest right over her heart.

She shivered; both from the chill of the disc against her chest and the thrill of having Simon hear how quickly her heart was racing. Biting her lip, Kaylee kept her gaze glued to his face, watching his expression for any hint of anything. All that she could see was that he was intensely concentrated.

Simon, meanwhile, felt his own heart responding to Kaylee's, racing almost in turn with hers. Her heart sounded incredible, the soft lub-dub echoing in his ears through the stethoscope’s earpieces. She had a strong, quick, healthy heartbeat and it excited him to know that it was pounding for him because he'd caught her off guard.

"You've got a wonderful heartbeat," Simon commented softly at long last. "And I think you look beautiful."

Kaylee blushed a deep crimson and giggled lightly, reaching up to place her hand over Simon's where he held the stethoscope to her chest. As apprehensive as she'd first been when Simon had caught her, she was ecstatic to be able to share her heartbeat with him so intimately, so unlike when he'd kept vigil over her after she’d taken a bullet to the abdomen during his first week aboard the ship. This time it was all personal and not totally professional.

She bit her lip as Simon slowly pulled the disc away from her chest only to resettle it a little lower, between her breasts. Goosebumps rose on Kaylee's skin at the contact and her heart skipped a beat. She smiled demurely and reached up, taking a hold of the earpieces of the stethoscope and carefully pulling them out of Simon's ears.

"When was the last time someone listened to your heart, Dr. Tam?" Kaylee asked coyly, tugging the chest piece of the stethoscope away from him as well.

Slipping the ear pieces into her own ears, Kaylee put one hand on Simon's shoulder and used the other to press the diaphragm of the stethoscope to his chest through the thin fabric of his shirt. It took her a second to move the disc around and find just the right spot but when she did, she was ecstatic to hear the sound of Simon's strong, steady heartbeat filling her ears.

Kaylee focused deeply on the sound of Simon's heart beating in hear ears, feeling closer to him than she ever had before. To be able to listen to the most intimate part of him was an incredible bonding experience and she only hoped that he'd felt the same way listening to her heart.

A minute or so later, Kaylee finally pulled the stethoscope aside once again and smiled brightly at Simon, leaning in to press a soft kiss to his lips. As she did so, she took one of his hands in hers, bringing it up to her chest and pressing his palm flat over her heart so that he could feel the beat there even if he could no longer hear it.

"That was amazing," she whispered to him, breaking the kiss but lingering scarcely an inch from his face. "When I could hear your heartbeat it just reminded me of how much I love you, and having you listen to my heart like that made me feel like you could see all of my deepest, darkest secrets."

"You can tell a lot from a person's heartbeat," Simon carried on softly. "But those secrets you’ll just have to share with me on your own another time. Now let's go enjoy the sunset on Beaumonde. We’ll have plenty of time for listening when we get back later."

With a bright grin on her face, Kaylee smiled and nodded. Simon reached up and took her hands, holding them securely in his as he helped her down off of the countertop and gave her a moment to balance herself. As soon as she was standing easily, Simon looped an arm through one of Kaylee's and led her out of the infirmary, out toward the cool pre-dusk on the beach where they'd landed.

As the two of them walked off through the sand, River peeked out from the doorway to the cargo bay, watching them make their way into the distance. She smiled wistfully as she listened to the waves crashing against the shore, sounding like mother earth’s heartbeat, the rhythm of love sounding for the two lovestruck children she held in her embrace as they strode along into the sunset.