CBS All Access's Star Trek: Lower Decks is one of the most unique Star Trek shows in the franchise's history. The animated show is centered on the lower deck crew of the USS Cerritos, rather than the bridge crew that most Star Trek shows focus on, This gives the show a loose and fun feel that pairs great with its comedic style.
The heart of the show is its cast, which is primarily focused on four of the lower deck crew, along with supporting characters from the bridge. All of these characters are tons of fun and incredibly charming, but that doesn't mean that some of them aren't superior to others.
Ransom
Ransom is the first officer of the Cerritos, and he's pretty one-dimensional when it comes down to it. That doesn't mean that he isn't good at his job, however. He cares deeply about the Cerritos, and wants to see it succeed in all of its missions. And while he works well with Captain Freeman, his relationship with some of the crew is pretty negative. He and Mariner are constantly fighting pretty much any time they speak, causing plenty of trouble throughout the ship. Ransom isn't a highlight of the Cerritos crew, but he isn't awful either.
Freeman
Captain Freeman is an interesting one. She tries her hardest to be as best of a captain as she can be to the Cerritos, but her less than perfect crew and the ship's low standing in Starfleet makes her one of the most unimportant captains there is. Any mission that the Cerritos gets is one that nobody else wants, much to the chagrin of Freeman. Nevertheless, she persists, even with her daughter Mariner fighting her order with every ounce of her strength. The two eventually figure their problems with one another out, even if it does take them some time.
Rutherford
Rutherford is a very nice guy, and that's about as detailed as you can get about him. He's sort of a blank slate, but he's always happy to go along with whatever plan his friends have cooked up in any given episode. Rutherford aims to please everyone as much as he can, and with the help of his implant, he's incredibly gifted with everything that he attempts to pick up. He might not be the most interesting member of the crew, but nevertheless, he's a great addition to the team.
Boimler
Boimler is the absolute antithesis of Mariner, 100% sticking to the Starfleet rules at all times, no matter the situation he finds himself in. This usually ends up being for the worst. Despite his desire to complete his duties to the best of his ability, he's usually sidetracked by Mariner or forced to break Starfleet rule in order to survive. In the end, however, his diligence is noted and he is promoted to a new role on the USS Titan.
Boimler might seem like a bit of a buzzkill at times, but he truly does care about all of his friends, especially Mariner, and wants to help them succeed in all of their goals. However, his dream of one day becoming captain will always come first to him.
Tendi
Tendi is an Orion who works on the medical bay on Cerritos, and she is absolutely precious. she can be described as a sort of Starfleet nerd, she absolutely adores her job and everything that goes with it. She's basically just very excited about everything that is going on aboard the Cerritos at all times and aims to do her best every single day. Even when she causes trouble, she works her best to resolve it as soon as possible. She is also, obviously, friends with Mariner, Boimler, and Rutherford, and cares about them very deeply. When Rutherford loses his memory at the end of season one, she enthusiastically begins to recount all of the memories that the two shared, which he listens to happily. No matter what task Tendi is faced with, she comes at it with everything she has in the most positive way possible, making her an absolutely joyful part of the Cerritos crew.
Mariner
Of course, the best part of Star Trek: Lower Decks is Mariner, beyond a shadow of a doubt. While she's an incredibly skilled individual and could easily become a captain if she chose to, she is a rulebreaker. She loves to get things done her own way, whether or not her way aligns with Starfleet's. This makes her a huge problem to her mother Freeman, who tries to get her transferred off of the Cerritos at every possible turn, until the two come to an understanding at the end of season one. While Mariner is certainly a troublemaker, she cares a great deal for her friends on the Cerritos, even if she does have a funny way of showing it sometimes. Mariner is a lot, but she's caring, incredibly intelligent, and an absolutely great friend. She is the heart of Star Trek: Lower Decks, and the series wouldn't even be close to what it is without her as part of the crew.