"Here now," McCoy was saying to no one in particular. He was lounging on Spock's bed, digging his hand into a bag of cat treats. Once he had gotten one out, he held it to the black cat beside him, who curiously sniffed at the snack before taking it into his mouth, chewing happily. McCoy grinned, reached his hand into the bag, and the process began again.

Spock watched the pair with vague curiosity for a moment before approaching and sitting beside the doctor. "What is the point?" he finally asked, watching as the cat scurried off with the last morsel.

McCoy raised an eyebrow at the Vulcan. "Point? He's a pet. He gets pampered. What more point do you need?"

But Spock shook his head. "A dog receives the treats as positive reinforcement for a learned behavior—"

"Here we go…" McCoy sighed out.

"—so that eventually they will perform that behavior without the use of a prize." Spock finished.

Raising a scrutinizing eyebrow at his companion, McCoy asked, "So what's your point, Pavlov?"

Spock decided to forego correcting the doctor — he was not a psychologist, he merely studied it — and explained himself instead. "The cat is performing no useful behavior. If one gives without a desired response, then what is the point of a positive reinforcement?"

Sitting up, McCoy shook his head with a tired sigh. "Damn Vulcan… It's a cat. Not a dog. Cats can't be trained like dogs can. Even if you give it positive reinforcement for a desired response, the cat won't care. He'll do what comes naturally and keep to his own ideas and rules."

Spock turned his gaze to the cat, now snoozing in the soft bed they made for him out of undershirts and an old pillow. He then looked back at McCoy, catching onto the double meaning of the doctor's words. "A cat can be taught," he argued, leaning a little closer to the doctor's face.

McCoy snorted. "Cats are arrogant, selfish, and very set in their ways. And they don't show affection very easily."

Ah, so that was it. The doctor was still smarting from their conversation the previous night. Without provocation, Spock pulled McCoy into his arms, murmuring, "Wani ra yana ro aisha."

McCoy was silent for a moment before returning the embrace. "I love you, too… I guess," he grumbled.

Spock pulled away, gently taking McCoy's hand and linking their forefingers and second fingers together. His kiss. He leaned in, planting his lips on McCoy's, tilting his head slightly to get the right angle. Slowly, he pulled back and whispered, "And that was my positive reinforcement." With a tiny Vulcan smile on his lips, Spock laid down on the bed, opening his arms for McCoy to join him.

Surprised, but pleased, McCoy snuggled into Spock's shoulder, chuckling. "Pavlov, eat your heart out."