All images: Paramount
It was recently revealed that the main character of Star Trek: Discovery, Lieutenant Commander Michael Burnham (Sonequa Martin-Green), was raised by Spock's parents and is, therefore, Spock's adopted sister. And my reaction was, "How many secret siblings does Spock have?" Because we've gone down this road before. It's been a long road getting from there to here.
In Star Trek V: The Final Frontier, we were introduced to Sybok, Spock's half-brother. I, like many a Star Trek fan, prefer to forget that movie ever happened. You can lift The Final Frontier out of canon with no serious effects, save regaining a bit of your sanity. But I buckled down and re-watched this thing the other day to remind myself about Spock's other unmentioned sibling.
I ... do not recommend it.
OK, so Sybok, in contrast to Spock, is a full-blooded Vulcan who is the son of Sarek. In the film, Spock describes Sybok as "a young student, exceptionally gifted, possessing great intelligence. It was assumed that one day he would take his place amongst the great scholars of Vulcan. But he was a revolutionary."
By "revolutionary," Spock means that his brother decided that the true path to knowledge wasn't logic but emotion, and he was banished for it. Spock also makes Sybok sound brilliant, which is... not how he comes across in this movie.
Sybok ends up on Nimbus III -- the so-called "Planet of Galactic Peace," and I wish I had a whole other article just to discuss how completely, utterly badly set up that whole place is. But, for now, understand that its major city is Paradise City, where, presumably, the grass is green and the girls are pretty. Sybok's meditations led him to get visions from what he believes is God and he launches a plan to go visit Him.
So Sybok takes hostages in, sigh, Paradise City, so that someone will send a starship to the Planet of Galactic Peace that he can hijack to go visit God at the end of the universe. By pure coincidence, the Enterprise gets sent to deal with this situation, and Sybok is delighted to see Spock again.
I get that Sybok is all into emotion, but the dude maybe should have held onto some logic, because when violence occurs after his army has taken hostages, he says, "It wasn't bloodshed that I wanted!" Logic might have told him that if he didn't want bloodshed, maybe invasion and kidnapping is not the way to go.
Sybok's telepathic ability is basically weaponised, involuntary therapy. He can unearth your greatest pain and share it and the resulting feeling gains him loyalty, I guess. Sadly, my greatest pain is this movie and he cannot take that away.
Part of that pain is this conversation that occurs after Spock doesn't kill Sybok and prevent the hijacking of the Enterprise:
KIRK: The man may be a fellow Vulcan, but that doesn't...
SPOCK: You do not understand me, Captain. Sybok, also, is a son of Sarek.
KIRK: He's your brother brother? You made that up.
SPOCK: I did not.
KIRK: You did too. Sybok couldn't possibly be your brother because I happen to know for a fact that you don't have a brother.
SPOCK: Technically, you are correct. I do not have a brother.
KIRK: You see?
SPOCK: I have a half-brother.
KIRK: I've got to sit down.
McCOY: Let me get this straight. You and Sybok have the same father but different mothers.
SPOCK: Exactly. That is correct. Sybok's mother was a Vulcan princess. After her death, Sybok and I were raised as brothers.
KIRK: Why didn't you tell us this before?
SPOCK: I was not prepared to discuss matters of a personal nature. For that I am sorry.
"I was not prepared to discuss matters of a personal nature" had better not be the explanation that Star Trek: Discovery uses to explain why Spock has another secret sibling. It may be canon, but it's dumb canon and no one likes it.
Sybok manages to get the Enterprise crew to take him to see God, who wanted Sybok to bring him a ship so that he could escape because obviously it isn't actually God, but a malevolent force seeking to manipulate Sybok into helping him escape his imprisonment. Kirk asks the famous "What does God need with a starship?" question that literally everyone ever should have asked, but everyone in this movie is at least half-stupid except for Kirk, because Shatner was in charge.
Sybok only manages to realise how badly he'd screwed up at the last moment, and sacrifices himself. And then no one ever mentions him again. Because The Final Frontier is a movie that no one ever wants to admit happened. And given that Star Trek movie canon includes Insurrection and Nemesis, that's quite an accomplishment.
And now Star Trek: Discovery is adding another secret sibling to Spock's life. Instead of a Vulcan with too much emotion, it's a human with too much logic. It's like Amanda and Sarek are playing Goldilocks with their children and only Spock managed to be just right. So long as Discovery learns lessons from The Final Frontier rather than taking any cues from it whatsoever, it might be an interesting move. It certainly couldn't go worse.