Beware Drusilla II

Daphne wanted nothing more than to slam it back on the table, but then she caught Drusilla watching her from the corner of her eyes, as though she was waiting for something.

That conniving witch of a half-sister! Drusilla must have been the one to lace her drink. She had been loitering around the dining table as she watched Daphne dance with the duke. 

Daphne thought she was looking for inappropriate behavior, but it turned out that Drusilla's plans were more insidious than mere rumor-mongering.

Turns out, she was watching Daphne so she could spike her drink with a potent aphrodisiac while her back was turned. If Daphne were to refuse to drink, Drusilla would probably attempt to corner her by making a scene. If Daphne continued to object, she would know that her scheme failed― and then Daphne would have to look out for yet another attempt.

It was easier to let Drusilla believe she had the upper hand.