Dive Deep into Creativity: Your Ultimate Tumblr Experience Awaits
Sonic and Knuckles are mountain man bros in the sense that they both grew up in the wild raised by animals. They dunk themselves in a river, call themselves clean, and then fistbump about it. They eat fruit right off bushes. Knuckles can find you a damn good tuber in a pinch and Sonic would be able to snatch you a worm if you really wanted it. Knuckles finds it difficult to pick up on mainstream cultural customs but Sonic's always found it easy now that he's older.
Tails and Amy, meanwhile, grew up in towns. These towns had a definite human influence, hence their possession of first and last names, but they still grew up in a Mobian in-group of sorts. They know proper fur/quill care, feel that it's gender non-conforming for a boy to wear clothes and a girl to go without them, and are adept at reading ear/tail gestures. Tails was never really one for any small-town slang but Amy still uses more rural phrasing even now that she lives in a larger city.
Rouge grew up in a large city, so she's more well-versed in cultures other than her own. She's adopted some human rituals because she thinks they're fun, like face masks and shaving some of her body fur. She loves exploring human cuisines because they're "exotic" to her while Mobian cuisine are comfort foods. She's fluent in several different kinds of slang along with the gestures/manners of the different cultures.
Shadow was raised by humans. His mannerisms are unmistakably human. From wearing human-sized shirts around the house, to having a taste for "human" comfort foods, to being completely unable to read ear/tail gestures in conversation, any Mobian is able to peg him as an outsider pretty quickly. While he's absolutely embraced proper quill care, Rouge had to first point out to him that he was doing it wrong- using human shampoo is not going to cut it, hun.
Omega is. . . weird. For the most part, he's predictably alien: what few social customs he's bothered to learn he has to have observed first. Rouge has been a helpful educator on the rare occasion he gives a shit, usually in regards to slang translation to add to his dictionary. He's almost more like Knuckles in the sense that he was isolated and now he's playing catchup. Sometimes, sometimes, though, the assumptions Omega makes will lean more towards human biases. Anyone who values their life knows not to ever point that out to him.
Metal Sonic reads like a robot imitating a human imitating a Mobian. Yes, he can imitate Sonic's gestures, but it's the movement in between that's uncanny. The physicality of his limbs. The weight of each step in his out-of-combat walk cycle. It screams "human". Most of his cultural knowledge, the little that he has, comes from observing Eggman's daily routine. But Eggman is just one human, and an isolated and eccentric one at that. Metal Sonic could recognize a refrigerator but not a washing machine, could recognize a plate and fork but not any other kitchen cookware. His knowledge is piecemeal. His imitations are incomplete. He was designed for combat, nothing more. His unconscious attempts to fill in the gaps are illogical, aren't they?
Silver is permanently locked into a culture called "survival mode". That's a joke, but only mostly. His behaviors more closely match that of someone growing up in extreme poverty. He can't stand to throw stuff away and he has a hypervigilance about danger that someone who grew up in a "bad neighborhood" would understand. Not to mention that any cultural values he has learned are a few hundred years out of date, so his guesses at any customs tend to be slightly off.
Blaze is from a different dimension, which basically reads as just a different culture than the one that's prominent where most of Sonic's friends reside! She actually gets a kick out of sharing her customs and comparing them to everyone else's. She's also from an extremely privileged walk of life, though, and it definitely shows no matter how much research she does to try and be less ignorant about how "normal" life works.