"What are you not looking at?"
No one likes to be ignored. Especially by a visitor in your own house. So it's understandable that this kitten might take offense when a "new cat" shows up with a bad attitude. The kitten may have been open to the idea of friendship at first, but after several seconds of the silent treatment from his impolite guest, it's on! Or at least as "on" as a fight can be when one of the combatants is an inanimate object.
So if you own an aggressive cat with too much energy and are thinking about getting a second one to keep him busy, consider going with ceramics. They don't eat or poop, and will make the first one feel like the toughest cat in the neighborhood.
(by Jonathan Corbett)