These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Kid vs. Kat
Ass Pull - At the end of "Class Act" Coop suddenly knows real magic for no apparent reason when he has to subdue Kat.
Millie, Lorne, Haley and Fiona suddenly getting all their memories of Kat being an alien erased at the end of the final episode.
Designated Hero: Millie. Whenever she doesn't get what she wants, she screams at the top of her lungs until someone caves in, and she just generally acts like a Spoiled Brat, yet she is loved by everyone, including Old Lady Munson (who hates pretty much everything) and Kat (an alien invader out to kill all humans), That alone almost qualifies her for Mary Sue status. In one episode, she finds out Coop was right about Kat all along, and she's... totally cool with it. And we're supposed to think this is sweet.
Fanon - It's a common assumption that Cat Commander is Kat's father.
Paranoia Fuel - Not only your cat, but also your hamster could be an alien invader. As Mr. Cheeks says, "We're everywhere"!