Although I speak some Japanese, I am not an expert in Japanese. I have never heard anybody say nii-kun. It’s a common failing of people in my situation to think that because they personally haven’t heard it, that it doesn’t exist, so I’m not going to say that, but even if it does exist, I don’t think -kun would be used.
“-kun” like you said indicates closeness and familiarity, but it also is commonly used for a business subordinate. Like, if you were at work, your boss might refer to you as “pivot-kun”, even if you weren’t that close. I don’t think Big Brother could ever be seen as a subordinate.
With my limited knowledge, if they wanted to use a Japanese word and not an English loanword, I think they’d use aniki or maybe ani-ue (although I’ve only heard these words in anime, I think people might actually still use aniki? It sounds like a Yakuza sort of word to me). These convey a respect that I think would be necessary for the mental image of Big Brother.


One of the things that’s generally effective when I feel nausea is to wipe my face with a cool cloth. I imagine that spraying water on your face might do similar.