Something I've noticed in the episodes since Diary of a Mad Cat is how thoughtful, kind, and patient Kitty has been to Dudley. In Freaky Spy-Day, she was especially quick to defend him from Jack. In Dog Tired, she was incredibly concerned when Dudley wasn't waking up, and was thrilled when he finally did. In Quack in the Box, she was patient with Dudley and his obsession with the Quacktionfigures, and didn't chastise him even after she thought he ejected her from the car. In Top Dog, she was also quite patient and non-critical of him, saying "It's ok, you did your best" after Dudley apologized for the poor job he did as the chief. In Cold Fish, she was patient with him and his dislike of the pants and was worried about him when he was freezing. In Lie Like A Dog, she didn't openly rip him for playing hooky, rather letting him be shown in a more passive way. In Candy Cane-ine, she also put up with him and his obsession with candy, gave him a new chocolate bar, and didn't even mind when Dudley asked her to carry him. Not much in Pup Daddy, considering she was a kitten for most of the episode. She did seem quite taken with him when she was a teenager, however.
I'm wondering if she's started to develop a crush on Dudley, hence her being nicer to him.
Interested to hear your thoughts!