Why does Dick Swiveller call the small servant the Marchioness?

The
small servant is a girl without an identity. She does not know her name. She is unaware even of
how old she is. As a result, Dick Swiveller calls her the Marchioness. He gives her this name
when the two of them are playing a game. She is reluctant, so he says that by giving her a name,
this will make the game more "real and pleasant" between the two of them.

Of course, the name is ironic, as it is not a proper given name at all, but a title for
nobility. A marchioness is the proper title given to the wife of a marquess. A noble knows who
his or her family is, as this is where they get their power from. The Marchioness is quite the
opposite.

It must be noted that it is hinted that the Marchioness is the
illegitimate child of the wicked Miss Brass and the downright evil Quilp (hence, her small
stature), so unlike a genuine noblewoman, her family line is not reputable or admirable.
However, Dick comes to love the Marchioness, valuing her as a person and eventually making her
his wife. To Dick, the Marchioness is just as good as anyone of noble heritage or legitimate
birth.