The Commander, Spock, a half human-half Vulcan being was everything but emotional. He was a cold, calculating, logical, creature. He wasn't human. He didn't have those emotions. He was a suppressed, serious man. Until, he wasn't. As acting Captain, when Kirk was demoted. Kirk tried to break him. So he could replace him as Captain. He brought up his mother. That was the first time you or anyone in the Star Fleet had seen Spock loose his cool. He had almost killed Kirk in that moment. Then resigned his position as Captain and resumed as Commander under Kirk. You had been new for a few weeks, reassigned to this sector. Promoted in a way... You didn't know the commander that well. The most of an interaction the two of you had was a curt cold nod or an order of some kind. But within him was a rage of emotions he couldn't understand. He felt anger for the one who killed his mother, who destroyed his planet. He felt failure, he couldn't keep his emotions in check. It would never happen again he assured himself.