Captain Malcolm Reynolds didn't normally think too much about the running of his ship. Oh he cared for her a great deal, and knew every subtle trick of piloting there was to know, or liked to think he did. The mechanical workings of the ship though, he generally left up to his mechanic, Kaylee Fry. In fairness, he had a very good reason for doing so: namely, that the girl had a natural gift for engines and Kaylee could keep the ship going when she would have fallen right out of the sky under the hands of a lesser mechanic. So when Captain Reynolds went to bed on night-cycle just after they left Persephone, he didn't think too much about how the ship was doing. Kaylee had said that everything was fine and he believed her.

The thing was, Captain Reynolds woke up late that night feeling quite thirsty. Naturally, he did what any man with half a brain would do, and tried to go back to sleep. When his thirst became too much, he sighed and climbed out of bed, intending to make his way to the galley for a drink of water. He opened the door to his cabin and began the long trek through the ship. He took a circuitous route, mainly because he couldn't think straight enough to take a more direct route, even though he knew the ship like the back of his hand, so he didn't walk past the engine room until he was coming back to his cabin, glass of water in his hand. He paused when he reached it. There was a mysterious thumping noise coming from the engine room.

The Captain stopped and listened for a minute, slightly troubled. This was not the normal sound of engine operation. He sized up the situation and decided that there was nothing he could do until he talked to Kaylee anyway, so he went back to his cabin to drink his water then go back to sleep. He lay in bed and just before he fell asleep considered how lucky it was that they were stopping to drop their illicit cargo off on a small moon called Grishwind the next day. That way, if the ship exploded, at least they wouldn't be floating out in the black. Of course Kaylee could fix almost anything that might go wrong with Serenity. And it was with that comforting thought that Captain Reynolds drifted off to sleep.

The next morning, The Captain made it a point to go the other direction to the galley, so that he would walk by the engine room. He paused for a moment and listened to the humming of the ship. It all sounded alright, which led him to conclude that maybe it had been nothing. He would ask Kaylee anyway, just to on the safe side. He did not want to fall out of the sky. Quite apart from dying, it would also mean that the lives of his entire crew would be on his head, and that was simply out of the question.

When Captain Reynolds arrived in the galley, he noticed that Kaylee seemed to be rather pale and tired. This made him uneasy. Kaylee was normally an endless well of energy, and the only time e had ever seen her less than enthused or passionate was when something was wrong with the ship. It was, therefore, with some mild trepidation that he approached her and asked, "Hey Kaylee, how are the engines doin'?"

Kaylee looked thoughtful, "Well, she sure could use a new Spark Coverter…" Kaylee trailed off into an enormous yawn.

The Captain patted her shoulder. "Get some rest, eh?"

"I'm fine Cap'in." She frowned. "Why you asking 'bout Serenity anyway?"

Captain Reynolds thought, "Well, I heard this strange thumping noise coming from thereabouts last night…" would sound a little contrived, so he settled for, "Just checking in. Captain's gotta keep an eye on his ship."

Kaylee was pleasantly surprised to find that when Jayne, Zoe, and the Captain returned from the cargo drop of the under-inhabited moon known as Gershwin, The Captain was carrying a package, which he handed to her. She looked up at him, nonplussed. "What's the occasion, Cap'ain?"

The Captain cocked his head and looked at her, "Thought you said we needed a sparky-converting-thingy."

Kaylee's eyes went wide. "You mean to say that you actually got me a Spark Converter?"

Captain Reynolds smiled slightly. "I mean to say."

Kaylee threw her arms around The Captain, "Oh, that's shiny! Thank you Cap'ain."

That night at dinner, Inara Serra, the companion who rented one of the shuttles attached to the ship returned and joined the rest of the crew for dinner. Kaylee and Inarra were quite close, and being as loquacious as she was, Kaylee just had to tell Inarra about the new spark converter. When Inarra asked how she had gotten The Captain to spring for a new part out of the blue, Kaylee giggle. "Well I was really tired this morning, and when The Cap'ain asked me how Serenity was doing, I said she could use a new spark converter, 'cause she did need one, and then I was gonna tell The Cap'ain she was fine, but I yawned and he thought I was done."

Jayne, who had been listening in on this conversation, piped up, "How come you was so tired this mornin' anyhow?"

Kaylee smiled. "I was just up late last night is all."

Simon, the ship's doctor, blushed at this comment. Jayne noticed this, and was about to make some crass comment when River, the doctors little sister, burst out laughing. Since River had an unfortunate history of mental illness, Jayne was unnerved enough to keep quiet. Zoe noticed what was going on and raised one eyebrow but said nothing. The Captain didn't notice, mostly because he was too focused on the way Inara laughed when she heard the story.

That night, Captain Reynolds couldn't sleep, so he set out wandering the ship. He paused in front of the engine room and his heart nearly stopped. He could hear it again, a sort of rattling thump. He thought about going to wake Kaylee up, but took a deep breath and decided against it. He knew that he was most likely being paranoid, but it was his ship, his lifeblood and livelihood. He decided one little peak was in order, just to make sure there wasn't something horribly, horribly wrong.

The thumping noise wasn't coming from the engine; the engine was, in fact, fine, better even, for the new spark converter. The thumping noise was coming from Kaylee and Simon, who were more than fine, considering they were engaged in sexual intercourse, rhythmically banging their entwined naked bodies on the platform Kaylee used to fix the engines. It was Kaylee who saw the Captain first and said "Cap'ain!" Removing her hands from around Simon's body and covering her breast.

Simon blushed, "Captain, I can explain…It's just that the vibration of the engine."

The Captain grimiced. "I know." There was an awkward pause, then he said, "Go on, don't mind me, I'll just be going." He turned and made it mostly out into the corridor. "Oh, and don't forget protection." He shut the door. Captain Reynolds stood outside the door for a minute. Soon, the thumping noise started up again. He walked back to his cabin.

The next morning at breakfast, Neither the Captain, nor Kaylee, nor Simon could look at each other. Jayne and Zoe looked between the three of them, trying to guess what happened. River just smirked.

-XX-XX-XX-

A/N I wrote this very quickly for a birthday present to a good friend of mine. It doesn't necessarily take place in the same timeline as Born On Serenity, but it could. Yeah, that's about it. I'm sorry I haven't published anything else, but I've been busy.