I don’t know if “platonic” is the right word for it, because it’s really familial. But if we’re defining “platonic” as non-romantic relationship, then I think Batman/Alfred is my favorite.
I just don’t think Batman as a concept would work for me without Alfred.
Alfred’s droll wit is only outmatched by his loyalty.
He is a balancing force for Bruce Wayne, and the rich playboy I think would have lost himself to his quest for vengeance a long time ago if not for Alfred.
Alfred has known Batman longer than anyone else, and I think because of that Bruce knows he can’t fake, bluff, or deceive the butler. He’s more genuine with Alfred than any other character.
And I think that’s because Alfred doesn’t see Batman. Everybody else that knows Bruce sees him as Batman. But I think Alfred just sees him as that little boy who plays dress up every night.
So yeah, I really love the relationship between these two.