Jim Kirk looked up from his work at his cabin desk computer.  "Spock, what's the date today?"

Spock sat on the other side of the desk, reworking the logistics of several planned temporal jumps on his tricorder. "Stardate 4133--"

Kirk cut him of brusquely.  "Not the Stardate, the date. The regular, landlubber Terran date.  In Riverside Iowa right now--what is it?"

Spock barely paused from his work. "Friday, February 28, 2268.  Why do you ask?"

"The computer is acting odd.  It's having trouble converting."

Spock set his tricorder down on the desk, next to his padd and stylus, and began his lecture.  "Possibly because it is a leap year in the archaic Gregorian calendrical system to which you refer.  As that system is significantly less precise than other methods of dating, even less so than much earlier systems such as the Mayan, it necessitated periodic adjustments for the inaccurate basal units.  The leap day accommodation that occurs every fourth year a is a highly illogical method of compensation, and might confound the computer's translation."

Jim stared at him and screwed his face, clearly puzzling over something.  Maybe it was his half-hearted attempt to decipher yet-another unsolicited treatise on arcane minutia; maybe something else was brewing in his brain instead.  However, when he spoke again, Spock got more questions instead of answers.

"Who told you that--about leap day, I mean?"  There was uncharacteristic tension in Jim's voice.  Enough to pique Spock's curiosity.  And, truth be told, perhaps a little concern as well.

"It is common knowledge, Captain."

Jim shook his head in flagrant disbelief.  "Maybe on Vulcan.  But you've been badly misinformed, my friend."

Spock's eyebrows began their upward journey.  "That seems unlikely, Captain.  I have studied the calendar systems of forty-seven Terran cultures with detailed investigation of several, including the Mayan.  I stand by my assessment."

Jim picked up the stylus and began to fidget nervously with it in his fingers.  He kept his gaze down and away. "Not the calendars.  I mean about the terminology.  About the leap year cycle.  It's not a mistake or a quirk of measurement."  Kirk paused, his face twitching with each stroke, as some covert internal battle seemed to play out inside his head.  He hopped up and began to pace the deck, his boot clicking with every step.

"It refers to a--thing--a thing that no outworlder may know.  A thing that has been passed down from the time of the beginning--before logic or science. Every fourth year human males must endure it. It is the human heart and the human soul.  And so the calendar was designed around it and leap day named for it, our--veneer of civilization. Can you not see that, Spock, and understand?  Spock!"  Jim grabbed him by the shoulders and shook him hard, staring him deeply in the eyes.

Spock reached back in his memories for a quick refresher of human physiology.  No phenomena fit the cross-reference criteria.  He then reviewed the differential diagnoses within human psychopathology.  A few definite possibilities popped up.  But this was his commanding officer and that maxim about discretion and valor clearly had some merits in logic.

"No.  I do not understand.  Explain."

Jim dropped his hands and paced back to the sleeping section, back to him as if in shame.  Spock waited expectantly, but no more seemed to be forthcoming.  He softened a little and moved his body in even closer.  "Would it help if I told you I would treat this as totally confidential?"

Jim hesitated. He stepped away and locked his hands behind his back.  His voice was barely a whisper when he spoke, still facing the cabin wall.  "It has to do with--biology."

"What kind of biology?" Spock asked, closing the distance between them again.  Their torsos all but touched.

"Human biology." Jim rocked on his heels.

Spock's eyebrows shot completely up under his bangs.  "You mean, the biology of Humans?"

Building up steam, Jim rambled on.  "Yes, the biology of Humans.  Biology as in--copulation." He spun around to face his audience. "On leap day, once every four years, partnered human males enter into the bon-abuddie fever--the time of rutting. At this time, copulation outweighs all other considerations."

For Captain Kirk, this sounded like an apt description of the standard day-to-day state of affairs. But for Leonard--?

Spock's eyes narrowed, and his voice could have cut transparent aluminum. "My mother did not tell me of this."

Jim bowed his head. "Perhaps she didn't know.  It is a deeply personal thing. A man understands, but even we do not speak of it, among ourselves.  You may not be a full-Vulcan, but neither are you a man.  If any human as proudly dignified as your mother were to have this secret ripped out of her--" Jim's voice trailed off.

Spock regarded him skeptically, the field of possibilities playing out behind his eyes.  He chose the most probable option. "Captain, you're making this up."

Jim donned his most sincere look of wounded indignation.  "Mister Spock, these things do not transcend the discipline of the service. I would never joke about something this serious.  There are precedents all through nature.  The birds and the bees, March hares and more. Why do you think so few Starfleet personnel are partnered, or why I never took a mate? Haven't you wondered?"

Spock answered without hesitation. "I believe the rest of us assumed it was because you lacked the requisite maturity necessary to sustain a healthy, stable, adult relationship."

Seeing Kirk reach for the stylus with anything but friendship in his eyes, Spock quickly re-evaluated his position.  They had both had the same combat training, but Kirk had far less compunction about the use of deadly force.  Spock backpedaled with impressive grace, giving pause to the conventional wisdom that Vulcan's cannot lie. "Or that considering the onus of Starship command, you have elected to make the ultimate sacrifice of personal life for duty and responsibility."

Jim's eyes hardened and flashed rapidly as an intriguing array of inner thoughts scurried across them.  Apparently he settled upon mollification.  His body relaxed again, appearing almost--Vulcan in composure and he shook his head ruefully.  "No, it was not. We shield it with regulation and blithe catch-phrases shrouded in antiquity.  You Vulcans have no conception."  Jim began to pace restlessly, up and down the small walkway between the cabin sections. At first he simply wrung his hands as he paced, then he began to gesture, flinging his arm a little wider with each step.

"It is by--necessity that we do this.  Human necessity.  It would wreak havoc on an active duty ship.  Losing you and Bones for a day--will be bad enough, but imagine if half the ship were affected--  It rips our minds from us--and leaves us at the mercy of our--glands instead.  Once every four years partnered human males enter into a sexual frenzy--and are driven by forces they cannot control--to leap on their mate and screw for hours on end." He dropped his arms and locked Spock's gaze hard with his own, eyes twinkling boldly with the usually vibrant energy.

And then it was gone, as if it had never been.  Jim plopped back down in the chair behind the desk.  He looked at Spock and shook his head dolefully, shame and resignation dripping from every pore. "I had hoped you would be spared this, but McCoy's drives will be too strong.  Tomorrow he must leap on you and take you repeatedly as a man takes a husband--or go mad."

Jim ceased to speak, and stared dully into his computer screen, his hands folded limp and useless on his lap.

Spock stood and inclined his head gravely. "Captain, I will see that the Doctor's leap day is handled efficiently--somehow."  And he turned on his heels and left the room.


Leonard McCoy came home to their quarters midmorning to find the lights down, the temperature set a little warmer than ship's standard, towels piled on the wainscoted ledge, and a naked Spock wide awake on their bunk.  Individually, none of these would have been particularly surprising, but as a combination, it was absolutely unprecedented.

"What the hell--  Don't you have a geophysics departmental review to conduct?"

As Spock sat up in the sheets, a fresh squeeze-bottle of Astroslick personal lubricant rolled a little way down the bed.   It was the economy-sized one.

"There is no need to be embarrassed about it, Leonard.  I have been informed of your impending leap-day crisis, and I have made arrangements to accommodate it.  It is not so dissimilar from my pon-farr cycle to which we will be subjected in a few more years.  In a way, I find it reassuring to know that this concept is not so alien to you as I had believed, and that we share this physiological need as well as our other similarities.  Although I fail to comprehend why you did not speak to me of it yourself."

McCoy sat down on the edge of the bed and ran one hand up Spock's inner thigh.  No point in turning down a chance to cop a feel, no matter how bizarrely it was offered up.  "Spock, nothing about you is alien to me anymore, except whatever in the blazes you are talking about right now.  What crisis?"

"Your bon-abuddie day of rutting and leaping.  It should, I believe, begin within the next few hours."

"Bone-a-buddy?--"  McCoy blinked incredulously.  "Spock, have you been sniffing my aftershave again?"

"I have not.  We can begin now, if you care to.  The superior stamina of my Vulcan physique makes the addition of a few extra hours of sexual activity inconsequential to me.  Although, I believe my human side might well appreciate the additional--opportunities."  Spock held out a hand to his husband.

McCoy rubbed his chin in thought.  "Jim, right?"  As he waited for the answer, he pulled off one boot and tossed it aside.

"Jim?" Spock queried.

"Jim.  Jim Kirk fed you this line, didn't he?"  McCoy worked off his other boot with his toe and kicked it across the deck to join its partner.

"It was the captain who provided me with the information, yes."

McCoy slapped the mattress. "I knew it!  That prancing, hot-blooded overblown little powder-puff of a Nero believes he has the right to manipulate everyone's personal life just with the flip of a toggle from the command chair.  I'm gonna kill the little rat!"

"For imparting critical information?  That is hardly logical."

"For his sick joke.  Messing with your head at my expense."

Spock furrowed his brow.  "Are you saying that there is no bon-abuddie phenomenon?"

McCoy looked his naked husband up and down.  He lay so open and vulnerable, purposefully exposed to McCoys whims, and McCoy felt the familiar flush that seemed to bloom fresh and new, taking him utterly by surprise every single time.  "Well--maybe not until now--" He lay down, running his hands through the course hair of Spock's chest, and kissed him deeply, regretting only that he had not made the time to remove his own pants first.

When they broke for air, McCoy added, "You say you have the whole day off."

"Forty-eight hours.  With the uncertainty of the Terran dateline and time zones, I was unsure as to how your body would be synchronized, so I left allowances.

"Logical.  Flawlessly logical," McCoy murmured into his neck, as he undid the seal on his own trousers and wiggled them down. "And it would be a shame to waste all that reconfiguration, wouldn't you say?"

But Spock didn't have time to produce an answer, for at that moment, McCoy leapt.