She let it slide with just a slap? Has she ever interacted with the weak minded type of "bully"? This maid angered her own boss, a noble, which in itself shows, she isn't just evil, but also rather stupid. That kind of personality will not accept being set into place, but try to take revenge. And that might happen in a cruel, dangerous and unbelievable stupid (and therefore surprising way). There is a reason, why big enterprises have the security guards accompany fired people to the exit. "Just a slap is enough for now" will invite trouble.