Commander Spock wasn't a jealous man. He wasn't, any emotion at all. He was just him. Half Vulcan, half human, emotional void. Almost everyone on the Enterprise was convinced there was nothing there. No emotion. Just an infinite void of calculation and logic. Only the rarest of times we say some sort of feeling flash across his face. But he was good as masking it. The best. Vulcans trained themselves to suppress there emotions. To control them. So that they never compromised anything. They could choose not to feel. Of course Spock had emotions and feelings. But he didn't show them. Never. He was cold, calculative, and commanding. Always a stoic expression on his sharp face. Due to his half human heritage it made controlling his emotions more difficult, but he was so strong willed. Not even a crack broke through. But when he saw Captain Kirk and you talking...and you...smiling... He felt something in his chest. In his jaw. He couldn't identify what exactly it was...but he didn't like it. You were the Lieutenant. A smart and strong crew member. Spock always appreciated your work and dedication even though he didn't show it or praise you. You thought he barely even knew of your existence. But Jim was obviously flirting with you, and you welcomed it. And he hated that. He convinced himself it was just because it was unprofessional and distracting. Illogical But even he has to admit that wasn't all it was...