How I think Kakuzu and Sasori interact/vibe
I think they would enjoy and respect each others more quiet reserved nature.
Kakuzu and Sasori would probably have a few inside jokes, i feel they both share a sense of dry humor.
I think they would both be a little curious and nosey about peoples personal business but really in denial about it. Like they LOVE eavesdropping on gossip or hearing the tea but try not to let others know. Especially because they would both be more private. And they would be reaaaally snack/strategic about any questions they ask people because they dont want to seem interested or invested even though they very much are. Like both 💯 want to know exactly why things went sour with you and your ex and where/what they up to now. They would probably low key gossip with each other and trade notes like crazy.
They might reminisce on vintage things. I mean not only is Sasori one of the oldest in the Akatsuki (even though hes not old at all or even half Kakuzus age.) but he was raised by his grandmother so i feel like he would be just a tad more familiar with Kakuzus generation than a few of the others. Like Sasori definitely grew up with some of Kakuzus behavior in his own house so he wont seem like such a relic to him compared to the way Hidan or Deidara might perceive Kakuzu.