Considering Historia was queen, it'd be a little suspicious to physically approach her for knockout purposes, so you decided to quickly walk into her room and drug her drink. It was just sitting there next to her small meal prepped for her on a golden tray at her desk. Looked like she had red wine with it. Perfect, the alcohol would make the sleeping drugs more potent. You slipped a tube out from your pocket and poured all the powder into the red wine, carefully stirring it in as you heard footsteps come up the door. You rushed out and shut the door behind you, standing at attention as Historia walked up.
"Good evening," she said with a soft smile.
"Good evening, Your Highness," you replied, "Did you have a productive day?"
"Very much so, thank you," she replied, "I have a great feeling about our new initiatives."
Historia went towards her door as you stepped out of the way.
"I probably won't be out anymore tonight, so you can rest up a bit if you'd like."
"Perhaps," you told her, "Good night, Your Highness."
Historia quietly closed the door behind her, but you had no intention of turning in for the night. You waited for a while as Historia, in the privacy of her quarters, consumed her meal and, inevitably, drank the drugged wine. You didn't hear much through the door, so you weren't sure if it worked...until you heard a thud. Something had slammed on the desk, and you were pretty sure what it was, but just in case, you knocked on the door to be sure.
"Your Highness?" you asked.
When you got no answer, you creaked the door open, and saw your prize; Historia Reiss, the queen of the walls, with her head slumped down on her desk out cold. The closer you got to her unconscious body, the more you heard sounds of her snoring.
"Guess those drugs worked better than I thought they would," you said, "You're out like a light!"
Of course, there was a matter of whether or not she should stay in that position while you had your fun.