Fandango/Ginko
who knows best what to say to upset the other?
who treats who’s wounds more often?
who boasts about the other more?
Full disclaimer, I have not posted the story in Countermelody where Ginkgo is introduced, but she's a main character of that series, acting first as Fandango's sex bot and later an employee of the tea house.
Who knows best what to say to upset the other? To be fair, neither really intentionally say things to upset the other because there's a lot of mutual respect in a sense (sort of. Fandango still sees her as a thing, but an object that does its job very well...). Fandango probably knows better what to say, since he realizes it upsets Ginkgo anytime he declines to interface or tells her there is no work, so he knows if he said she was fired, it would severely hurt her. He's not going to do that though. Ginkgo probably has a sense that saying anything about Fandango and Scaramouche being related might be bad, but she doesn't know who to say it to to upset Fandango.
Who treats who’s wounds more often? This is a toss up, only because Ginkgo is the one that helps prevent Fandango from getting injured when he crashes (her working at the tea house means Fandango doesn't have to work as hard and gets more recharge, which in turn leads to him crashing significantly less). Technically, Fandango does treat more wounds because Ginkgo will only alert others if Fandango is hurt and just sits with him. Ginkgo does get hurt by others who attack her and Fandango patches up small wounds and a couple of larger ones before making sure she is set up with a mechanic.
Who boasts about the other more? Hands down, Ginkgo. She will constantly talk about how wonderful Fandango is every time she is with Jared or Francis. She absolutely loves and adores him. Fandango will occasionally praise her, but Scaramouche has to pry that out of him.