I have pulled the following back story for this picture out of my toches:
Mami was decapitated by Charlotte, but not killed, since her soul gem was not damaged. She regenerated, befriended Charlotte, but is of course pissed at her for nearly killing her, so she serves her tea from a bottle, which is, like tea from a tea bag, a total sacrilege against tea to a tea connoisseur like Mami.
