Avoiding each other, for the First Officer and Chief Medical Officer aboard Starfleet's flagship, proved far more difficult than expected.

Asides from times when their paths crossed accidentally there were inevitably occasions where they were both required.

Staff briefings for one, although McCoy tried very hard not to notice the Vulcan was even there. Spock for his part seemed able to exert Vulcan control over even his body's involuntary functions. McCoy vindictively hoped the effort tired him out although he showed no sign of it. McCoy was positively drained from holding his own emotions so firmly in check.

There were also sundry activities where the presence of both senior officers were required. McCoy was sick of people smiling as they asked if he was letting off steam.

And at the end of a week Bones was beginning to suspect the captain was enjoying their predicament too much.

McCoy himself was most certainly not enjoying it. In fact it was probably the most hellish week he could remember.

It wasn't just the added tension of trying to avoid Spock – changing his mealtimes and routine to keep their paths from crossing – or the frustration of not being able to visit the bridge when things got slow in sickbay. It wasn't even the headache of keeping his focus from the Vulcan when they were in the same room… no it was the sheer fact that he missed the man.

Although he didn't think he'd ever have admitted it, Spock was one of his best friends. He could always speak his mind with Spock knowing that he'd get an honest reply. It generally wasn't a reply he'd agree with but it helped reinforce his own thoughts. If he could successfully argue his case against the Vulcan then he knew his position was entirely valid. If Spock could pick his argument apart then it was probably as well to rethink.

There was no-one else on the crew with whom he could rail so emotionally either. Anyone else would either be swayed into his own emotional maelstrom or be turned away by it. Spock was a rock. An anchor. McCoy could rant at him full force for upwards of fifteen minutes and receive nothing but an eyebrow for his trouble yet he'd go away calmer.

Now he was trying to do without a coping mechanism that he hadn't even realised he needed. Christine was getting snappy with him, unwilling to put up with his short temper.

Strangely, he now appreciated there were the quieter moments between them that he never usually thought about or even realised happened. Especially when they were conducting research.

McCoy had worked on the problem in the medical labs while Spock had studied the problem in the science labs and, while they understood how the powder had integrated their bloodstream and bonded chemically to produce visible pheromones, there seemed no way to reverse that bonding. It was in Spock's words an irreversible reaction that they would likely have to wait out. That conversation had proved two things. Firstly that Spock was likely correct and secondly that the glitter effect could be produced even when communicating by comm.

McCoy had been mildly gratified to note that Spock had not anticipated that and thus had not been so rigorous in controlling his own reaction.

It was a short lived triumph.

So Bones was now slouched in his quarters wondering just how long they'd have to do this and beginning to regret suggesting it.

Surely just walking together to the messhall in the morning wouldn't cause too much embarrassment? And couldn't it be argued that the only way they'd ever purge the powder would be to hurry up the pheromone production, not suppress it?

When the room chimed he sat up with the hopeless thought that perhaps Spock had come to suggest the same thing.

"Come in," he called, even as his mind reminded him that Spock would be playing chess with Jim this evening.

It was to his great surprise then that he saw Jim in his doorway.

"Jim! What are you doing here? Thought you'd be getting beat at chess tonight." His warm smile dissolved into a worried frown. "Is Spock alright?"

"Fine, he's fine," Jim waved reassuringly and McCoy's eyes fixated on the bottle being waved in his direction. "He headed back to his quarters early and I thought you might appreciate a little company."

McCoy waved his own arm, gesturing Jim to make himself at home. In truth he was emotionally exhausted and couldn't really muster the energy to play host. Luckily, Jim knew him well enough to not be offended in the least and quickly got them both glasses.

After pouring two generous helpings Jim began again.

"Actually, I beat Spock for a change tonight."

McCoy arched an eyebrow.

"Something for your log," he drawled.

"He doesn't win all the time," Jim insisted briefly before taking a quick swallow. "But he did seem somewhat distracted tonight."

McCoy silently contemplated that piece of information, covering his thoughtfulness with a slow drink from his glass. He was aware of Jim watching him.

"Probably frustrated he can't pull a scientific miracle to prove me wrong about waiting out this Fesarian 'gift'," he suggested.

"I thought he'd suggested it was irreversible?"

"Yeah but I said we should wait it out."

Jim looked down and swirled the remainder of his drink.

"You still sure that's the best solution?"

McCoy hesitated.

He'd just been thinking about that very thing of course. But it was one thing to acknowledge a possible mistake to himself, a very different thing to admit it to anybody else. And McCoy had always been far too stubborn for his own good.

"The way I see it, if it weren't logical, Mister Spock would have already suggested trying something else."

"And what if Mister Spock just thinks he's being considerate of your emotional human needs?"

"He ain't ever been considerate of my emotional needs before."

"There's a first time for everything."

McCoy glared at Jim over the rim of his glass before aggressively downing it.

He wasn't even sure why he suddenly felt so angry. Except that he'd been tense the whole week and was bone tired now and it would be so easy if he could just stop fighting his own responses.

"Thanks for the drink Jim but I just really want to turn in now."

Jim seemed to contemplate saying something further but apparently realised it wasn't the time.

"Sure," he agree easily, rising casually. "Just… think about other options alright? You can't avoid each other indefinitely."

McCoy nodded vaguely and let Jim see himself out.

He knew the damn man was right. As captain he'd already bent the rules for them more than he perhaps should. But the only other option McCoy could think of meant admitting just what pheromones were involved here and why.

He wasn't sure he was ready to do that.

And it wasn't like Spock wouldn't have already analysed the human pheromones and drawn conclusions. Damn Vulcan wasn't mentioning that though for which McCoy was both immensely grateful and deeply crushed. It wouldn't be so bad if he could analyse the Vulcan sample the same way but there was no information anywhere he could trace of the chemical properties of Vulcan pheromones.

And asking Spock would just open the whole embarrassing subject.

McCoy dragged a hand over his tired face and dragged himself up. He'd best try and get a good night's rest.

Seemed like he'd have another day of avoiding the First Officer tomorrow.