Question about Pure Bloods and House of Slytherin

[Carol]

Kemper wrote:
> But the phase suggests more than one, 'enemies', and there are not
two or more Mr. Filches.  Unless you are saying that it is Mr. Filch
and Mrs. Norris who are the 'enemies'... which honestly, doesn't sound
very reasonable even for Filch.  Plus, the cat was already taken out,
so the phrase would have to change to 'enemy' of the heir.
> 
> I think it is more reasonable for Mr. Filch to have heard of the
Chamber of Secrets and what had happened 50 years earlier to a
Muggleborn witch in the girl's bathroom.

Carol responds:
I think that canon supports this interpretation since Memory!Tom
himself says that Ginny "set the Serpent of Slytherin on four
Mudbloods and the Squib's cat: (SS Am. ed. 310). So Filch, who, as
Kemper has already pointed out, is upset that Harry has seen his
Kwikspell catalogue and thinks that Harry is the Heir of Slytherin,
thinks that he's an "enemy of the Heir" not because all the students
hate him but specifically because he's nonmagical and, in the eyes of
Slytherin's heir, an inferior being. Filch is lucky that his cat
rather than he himself was the first victim.

Carol, who thinks that "Enemies of the Heir" primarily means
Muggle-borns but would include Squibs as having no rightful place
within Hogwarts in Slytherin's view (or his heir's)