cat and mouse friendship

these cute animals used to be enemies... but they have now signed a peace treaty to be best friends.
How? Well, it's actually down to science. Mice fear cats because they are innately conditioned to express fear when they sense the odour of a predator. So, if you take away these specific receptors for sensing odour, mice never feel afraid of cats.
BUT, why the cat doesn't fear the mouse is a lot simpler...
The cat was chosen because she's just a really friendly kitty.