How we cite our quotes: All quotations are from Star Trek V: The Final Frontier.
Quote #1
KIRK: What is it? You look like you've just seen a ghost.
SPOCK: Perhaps I have, Captain. Perhaps I have.
Although it takes some time for the truth behind Spock's relationship to Sybok to come out, our favorite half-Vulcan is immediately shaken by the sudden appearance of a "ghost" from his past.
Quote #2
SPOCK: He reminds me of someone I knew in my youth.
MCCOY: Why, Spock, I didn't know you had one.
SPOCK: I do not often think of the past.
Why do you think Spock doesn't "often think of the past"? We have an idea: it bums him out. Though it's easy to stereotype Spock as cold and unemotional, he clearly has a mess of conflicted feelings about years gone by.
Quote #3
SYBOK: Spock, it's me. It's Sybok. After all these years, you've finally caught up with me. Don't you have anything to say to me?
SPOCK: You are under arrest for 17 violations of the Neutral Zone Treaty.
Not exactly a warm, brotherly reunion, eh? From our perspective, this further emphasizes Spock's disconnection with his past. Sure, we don't expect there to be hugs and high fives after Sybok just took over a planet by force. That'd be a bridge too far. Despite that, it's weird that Spock acts like he doesn't even know his half-bro.