Many times in the series, Mabel's love of "creepy vampire romance novels"(ie. Twilight) has been referenced

But look at this quote from The Last Mabelcorn:

Mabel: Are you gonna tell us we're finally of age to go to wizard school? IS THERE AN OWL IN THIS BAG?!

That, obviously, is a reference to Harry Potter

Yes

She likes Twilight AND Harry Potter.

And if I know one thing about the two, it's that if you're in one fandom, you despise the other.

Yet she doesn't.

And I think that's awesome.