Just as Harry has his nemesis in Draco, Hermione must have a nemesis as well, and apparently Pansy is selected for that role. We don't, however, see as much of her as we do of Draco; this may be because Hermione is playing a supporting role. However, Pansy's bullying behaviour, directed at Hermione among others, serves a larger purpose: the author is using Pansy as a way of showing that Draco's ongoing attacks against Harry and other Gryffindors are not a characteristic of Draco, but of Slytherin house as a whole. It is the [[Muggles' Guide to Harry Potter/Characters/Sorting Hat|Sorting Hat]] who tells us, in ''Harry Potter and the Philosopher's Stone'', that
:''These cunning folks use any means, To achieve their ends.''
There is not anything inherently evil in this, but it does easily lend itself to abuses. In the case of Pansy and Draco, clearly the means used for advancement include putting down other students. It seems that having Pansy act in this way is intended to show that this sort of behaviour is accepted in Slytherin house in general.
