Is there a name for the literary trope where two characters are meant to be seen as a pair with complimentary attributes, but a deeper link?

I'm thinking of something much beyond the Nero Wolfe/Archie Goodwin type relationship. A good example of what I mean is Hollis Henry and Heidi Hyde from William Gibson's Zero History. The pair of alliterative names could be a hint. And each seems too extreme a character in their personalities. I feel the author is pretty good at writing characters that aren't one-dimensional, but Hollis seems way too cerebral and Heidi way too action oriented.

Thanks!