Si and Am

Si and Am are Aunt Sarah's two Siamese cats and antagonists from Lady and the Tramp. Both were voiced by Peggy Lee. They were later voiced by both Mary Kay Bergman and Tress MacNeille in the sequel; MacNeille now voices them both since Bergman's death.

Development
Earlier versions of the storyline, drafted in 1943 during the war, had the two cats appear as a sinister pair, suggesting the yellow peril. They were originally named Nip and Tuck. In Ward Greene's novelization, they tearfully express remorse over causing the Tramp's impending execution by hiding the rat's body as a joke, and then try to make amends, while in the film they do not partake of the climactic scene.

Personality
Si and Am are sinister pair of cats who use the love they gain to get others into a large amount of trouble. The cats are sneaky and love to cause trouble and make messes for their own amusement. It is indicated that they care for nothing but each other and takes advantage of Aunt Sarah seeing her as a protector and not a beloved owner.