ok but consider uncle takasugi and shinpachi & kagura:
uncle sugi and the kids trash-talking gin. at every. chance. they. get.
uncle sugi treating the kids because gin is too lazy and practically forced him to (plus takasugi won’t admit that shnpachi and kagura are actually pretty nice, for a couple of brats), but his idea of “treating” is buying boxes and boxes of yakult bottles and frozen yakult pops. (kagura pretends to hate them, but food is food, right? but just when she leans over to grab one, shitsuke decides to drain every last bottle in one sickly gulp. and then promptly gets beat up by kagura, much to gin’s enjoyment)
kagura complaining about kamui/narrating all the embarrassing childhood stories to takasugi, and him taking note of each and every word to use as blackmail material
kagura scaring takasugi with stories of how matako watches him when he’s sleeping, keeps his old yukatas, etc.
takasugi telling henpeita to stay away from kagura if he doesn’t want gin to destroy him
shinpachi impressing uncle sugi by telling him how he and tae are trying to save the shimura dōjō and help others learn swordsmanship and calligraphy, and takasugi being reminded of what shouyou did for him
takasugi coming over to check on them once in a while, with bansai and zura/elizabeth helping out with design plans, fundraising, recruitment, etc.
uncle sugi and dad gin competing over who can impress the kids more.
uncle sugi, being one of the top-ranked characters despite having 3 minutes of screentime in three seasons, giving advice to pachi on how to be a more “interesting” character, but finally telling him that he wasn’t really ever boring, in the end
uncle sugi coming over to play some shamisen for the kids on bad days, and gin listening from the room next door
uncle sugi telling the kids about the famed shiroyasha, and what gin had to endure throughout his life