So... what does the Captain think of his crew? Well of course he respects them and loves them and is like a second father and all that, but I'm more talking about his deep admirations and dislikes of their habits.
Alright, here we go.
KWAZII: The Captain has many many pet peeves about Kwazii. A big one is when he explicitly doesn't listen to what he says over and over and over. Fair enough. Sometimes the Captain just wants to have a break and send Kwazii on holidays for a week, but he's afraid that Kwazii will return in pieces. The Captain also hates it when Kwazii picks on the other Octonauts, like telling Peso scary stories or teasing Shellington and Dashi about their relationship, which is honestly a valid opinion towards this behaviour. I hate it too. A less rational pet peeve is annoyance at Kwazii's pirate talk. Random, the Captain admits it, but he just hates it for some reason. He likes Kwazii's competitiveness, and secretly loves it when they challenge each other (except for table tennis, he always loses at that). He also envies Kwazii's youth and agility.
PESO: Peso is a magical healer gifted with alien medicine in the Captain's eyes. How does he fix literally everything with just a bandage? Barnacles just shakes his head in awe. He doesn't get annoyed by the little penguin at all. His emotions towards Peso are just fatherly protectiveness and constant amazement. That's all there is to be said about this, other than that it's the cutest, most loving, FATHERLY AND PLATONIC relationship in the fandom by far.
DASHI: The Captain is very thankful he has Dashi, and he doesn't understand how she keeps going. Pet peeves? He hates shopping, and dislikes it when Dashi drags all of them along to her favourite stores. He dislikes her dog habits like barking and getting distracted by small moving objects. An exception is her wagging tail, which he finds hilarious. He does also wish she'd stay on topic whenever Shellington's name gets mentioned, however. Barnacles thinks that Dashi is a wizard who doesn't need sleep and is magically keeping herself alive. Fair, she goes through a lot with not much sleep and is fine. When asked, she just says she's Aussie, so Captain Barnacles just takes that as the answer. In his eyes, Aussies can't be killed. Anyways, he also loves it when she scrapbooks, they often have hot-chocolate-and-reminiscing sessions together, often with another Octonaut. He admires the can-do attitude Dashi brings into literally anything.
SHELLINGTON: Captain Barnacles is kind of fatherly towards Shellington. He is very proud of how his surrogate son has developed, finding out all sorts of thing the Captain can't begin to wrap his mind around. Most of the time he just accepts Shellington's word as gospel truth. At least, when it comes to science. He won't if it's literally anything else. The Captain is constantly concerned for Shellington's wellbeing, physical and mental. Things that piss Barnacles off? Probably when Shellington doesn't care for himself. When Shellington is clumsy and accidentally endangers the lives of other Octonauts, said other Octonauts always immediately forgive him. When he endangers himself, however, the Captain and Dashi won't let him forget it. Also, Captain Barnacles loves the way Shellington gets lost in his research, but often wishes for Shellington to have a bit more focus.
TWEAK: Like Peso, Tweak's a bit of a wonder-worker according to Cap. He's never dipped into the world of engineering, so all of the things she does are inexplicable but amazingly helpful. So he just takes them for granted. But he certainly has his peeves when it comes to her. Barnacles hates it when she's stubborn and argumentative, especially against Kwazii and herself. Her insults and language are deemed inappropriate for the Octopod by the Captain, who has made her change her swearing ways. Additionally, the Captain disapproves of the way Tweak takes care of herself, but he knows that her aforementioned stubbornness will keep her from listening to any advice he or Dashi give her about self-care.
INKLING: The Captain truly respects Inkling, as a colleague of his mentor and a wise trainer in of himself. He and the Captain, as the two eldest on the Octopod, share a love of sea stories (real ones, not Kwazii's) and a good chat over some books and hot cocoa. As such, the two of them have grown very close. The one true pet peeve Captain Barnacles has for this kindly old octopus is perhaps his slow use of technology, which is decidedly unhelpful in a situation like the ring of fire, where the Captain really needs Inkling to step up and act as soon as he can. The Captain admires Inkling's wisdom and experience.
TUNIP AND THE VEGIMALS: The Captain only has a bounding and overwhelming love for these little guys. And perhaps a slight bit of annoyance when they lose his octo-compass.

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