Sylvia's eyes widened in surprise. She didn't know what had caused her friend to faint, and she thought the poison from the needle wouldn't possibly cause anything to a Human Emperor's body...
This was indeed a sudden attack of things she didn't expect. Still, it didn't mean she had much experience either, basically...
However, what the Devil Princess had in mind was a broader matter than simple things. She thought her Human Emperor friend pretended to be unconscious on purpose to find out who was behind it all.
Plucked to the root or something like that, it was also nothing without careful consideration. Judging from the two attackers' intentions and the thief boy, Sylvia knew they had no killing intent...
So, because of that, Sylvia followed her friend's method by pretending to be fainting like an ordinary girl poisoned by sedative poison.
^_^