Spock was avoiding Bones after the incident on Sarpeidon... unsurprisingly but unfortunately. Eventually he had no choice but to ask Kirk to order Spock to sickbay; he had news to share with the Vulcan.
"What is so important that you had to ask Jim to ask me to come to the bridge?" Spock asked once in sickbay face-to-face with the doctor.
"Well, I figured if I asked you myself, you might not come, since you're still hung up on what happened at Sarpeidon. Spock," Bones interjected as he saw the Vulcan open his mouth to speak, "I really don't want to argue with you about it right now. I was doing some research and I found out something that might interest you."
"And what would that be, Dr. McCoy?"
"I was wondering why you had a personality change in the ice age and I didn't. After all, it does seem like that should have been the case. As you might have guessed, it has to with Vulcan physiology as opposed to human's." He pulled a disc out of one of the sickbay computers. "Here's all my data findings on the phenomenon."
Spock took it, looking almost confused. "That's... very thoughtful of you, Doctor."
Bones smirked. "Well, I thought you'd want to know."
