Sometimes you just have to shake your head at the folly of these cats. Tan doesn't like other cats. Dewdney knows that Tan doesn't like other cats, Tan has made this abundantly clear to Dewdney.
This knowledge does not prevent Dewdney from using her head to wheedle the door open and sneak out.
Once Tan discovers this she has to express her displeasure with hissing, chasing, and growling until Dewdney flees or sulks back into the bedroom, depending on her mood. Now we can't blame Dewdney for all this behavior. Even though Dewdney is the one escaping from the bedroom and Tan is the one chasing it must be said that Tan does a little taunting of her own.
Eventually she gets bored and goes away... but she always comes back.
I don't even try to understand them sometimes.
