Why is there a cat behind the Tarot Queen?

You mean the queen of scepters, right? There is a black cat on it. The specific explanation is as follows:

The queen of scepter represents a strong and straightforward woman. She likes her independent personality and encourages people around her to do so. She is willing to act and organize, and may ignore that sometimes others don't ask her for help.

The sunflower on this card symbolizes her vitality and positive attitude, while the black cat symbolizes her intuition and can protect her from harm. The lions on both sides of the throne represent her inner strength. Lions can be seen in the power card, and the power card and the queen of scepter all symbolize Leo. Another card belonging to the same symbol in astrology is the sun.