Full Idea
For Aristotle what makes a friendship a virtue-friendship is the binding force within it of some - perhaps for all that partial and incomplete - excellence of the character.
Gist of Idea
For Aristotle in the best friendships the binding force is some excellence of character
Source
comment on Aristotle (Nicomachean Ethics [c.334 BCE], 1156b10) by John M. Cooper - Aristotle on Friendship p.308
Book Reference
'Essays on Aristotle's Ethics', ed/tr. Rorty,Amélie Oksenberg [University of California 1980], p.308
A Reaction
It is certainly hard to imagine a really good friendship that doesn't involve mutual respect, and possibly even mutual admiration.