>>69436669I'd have linked the Mario Party stream they did together in her indie days, but it appears to have been privated. That's the most Anemachi we have ever seen in one stream. I'm sure you've seen clips from it, at least. It shows a side of her that's not often shown, and in general Anemachi is a pretty private person. She deliberately shows up less these days, she's more conscious about how chat treats her like a celebrity.
Some of Suisei's bad habits are due to Anemachi's influence, ie. you probably already know that she's a huge fan of BL and that she dislikes vegetables about as much as Suisei does. Anemachi is in charge of cooking, loves ponzu sauce and likes to stick to scheduled meal planning.
For your story, you probably want to embellish their co-dependency. During the HoloHouse period, it was Anemachi who refused to let Suisei move without her. At the same time, Suisei relies on her, even if Suisei can be a cheeky little sister who won't admit that openly. That cheeky side of Suisei shines through in that Mario Party stream, I feel.