Compare colonel Pickering and professor Higgins in Pygmalion by G. B. Shaw.

You already have a very thorough discussion of these two
characters in Pygmalion.  I would simply add a couple of things.
Pickeringis, indeed, a rather harmless foil to Higgins, and he is the one who treats
Liza with respect and dignity.  She is quite clear as she talks to the Colonel in Act
V--she is appreciative of his help and recognizes he would have done the same with
anyone because that's just who he is.  On the other side of that, though, he certainly
could have limited Higgins's bullying and nagging.  Instead, he benignly watches the
process and doesn't intervene much at all.  It's true that Liza was not in mortal
danger, of course, but he certainly could have been more involved and shown more
compassion.  It works out, though, and Liza is grateful.  She says to
him: 

You
see, really and truly, apart from the things anyone can pick up (the dressing and the
proper way of speaking, and so on), the difference between a lady and a flower girl is
not how she behaves, but how she's treated. I shall always be a flower girl to Professor
Higgins, because he always treats me as a flower girl, and always will; but I know I can
be a lady to you, because you always treat me as a lady, and always
will.

Higgins is a bully, but
he got the job done.  He does so rather heartlessly, treating Liza as an experiment
rather than a fellow human being.  In fact, when she points that out to him, Higgins
proudly proclaims that he treats everyone that way--king or peasant is all the same to
him.  This is his flaw, of course; people don't really matter except how they fit into
his plans.  (Just ask his mother--she would
agree.) 

Perhaps it is true that these two men are two
sides of a coin or two parts of a whole.  If so, they can both take credit for the
accomplishment of turning Liza into a "lady."  But only one of them does, of course, and
that's Higgins.