i think rook's implied isolation/loneliness is genuinely such an important part of his character that people NEED to focus on more??
rook is constantly isolated from the people around him, both by circumstances and by choice. his family is always busy and away from him, causing him to regularly be on his own most of the time (rook literally says theyre so busy they can all reunite only once a year, he can't remember the last time he had his birthday celebrated outside of nrc, AND he would spend the entire day of his birthdays at the theatre alone🙁) and he's been shaped by that emptiness. being solitary isn't new to him, it's all he knows.
this isolation is also further exemplified by his own social issues - rook is constantly avoided by others for being too weird, too off putting, too much. as fully confirmed in book 8, rook was completely alone the entire time he was in savanaclaw due to being cast aside by his other dormmates, and we can likely assume this has been the case since way before nrc. before vil, who very well might've been the first person ever to embrace rook in his entirety, eccentricities and all, rook pretty much had no one.
at the same time though, rook feels a need to keep people at an arms length. and this isn't just purely fueled by him wanting to seem unpredictable (although that could be part of it), it's genuine discomfort. some of the ONLY times we see rook beginning to break away slightly from his calm exterior is when he's being pried for details on himself. a great example of this is in spectral soiree, where he tries to find excuses, gives only vague answers, and begins to actually appear stressed?? rook isn't someone who at all, wishes for others to know the truest, rawest parts of himself, despite so adamantly admiring those aspects in others.
in short, i think its so interesting how rook is a person who was grown from isolation, both in his familial environment and just generally socially. but now, even being surrounded by several people who truly love and care for him and his interests, he's still a one way mirror. he'll always still find a sort of comfort in that isolation, in the way that he'll be able to hide the purest aspects of himself in it.
