Season 2 of Star Trek: Discovery has been a fun ride so far, but some recent news has revealed that a bit of that fun will fade at the season's end. Two major characters from the Star Trek lore have been confirmed to be shipping off ahead of Season 3, and presumably heading back to the Enterprise to live out the rest of their fates. Anson Mount and Rebecca Romjin, who play Captain Pike and Number One, will leave Discovery.
Though Anson Mount's Captain Pike has been pretty popular amongst Star Trek: Discovery fans, Deadline reported he and Rebecca Romjin's contracts are strictly one year contracts intended for Season 2. As far as why, it's being said that the season's intention was to fully sync Discovery up, which is currently somewhere between the failed pilot "The Cage" and the episode "The Menagerie" at the moment within the original Star Trek series lore. What does this mean for the two characters?
We can't say for sure, although it is known that Pike gets a promotion to Fleet Captain within Starfleet but is ultimately forced to relinquish command due to an accident that leaves him badly injured. Pike is later taken by Spock to Talos IV, which was featured in the aforementioned Star Trek episodes as well as a recent episode of Discovery. There, Pike is able to live a life free from injury, thanks to the psychic projections of the Talosians.
Number One's fate is uncertain, but she's no longer around the Enterprise by the time Captain Kirk rolled into Star Trek. Whether she left the ship after Pike, or something will happen to her before the end of Season 2, we'll have to wait and see. Number One is not a major character within the franchise lore, although her title was used frequently in Star Trek: The Next Generation to refer to William T. Riker.
One interesting thing to note about this bit of news is that nothing was said of Ethan Peck's Spock. Spock is obligated to his duties on the Enterprise, so if Pike is returning, it's presumed Spock would do the same once the Red Angel mission is over. Of course, Star Trek has done some crazy things in the past, and there's no canon that explicitly states he has to be there any amount of time beyond Kirk's arrival on Enterprise.
With that said, Spock doesn't seem too keen on hanging out with his sister Michael. The two have been going round and round airing out grievances with each other in a mix of Vulcan logic and human emotion. Chances are they'll eventually find a way to reconcile their feelings, but even then Spock really has nothing tying him to Discovery after his name is cleared and his mission is complete.