Try to drop a crystal in her drink

Carefully you reach into the small pouch and remove a single crystal pinched between your thumb and index finger. You look at woman and see you can easily put the crystal in her drink without her noticing. You walk past her, dropping the crystal in the glass as you go, "Thanks for the information." you say as you walk away.

"No problem." she says, never even opening her eyes.

You walk some distance away and take a seat on one of the chairs in the garden. She rolls over and reaches for the glass. Your breath catches as she looks at glass and for a brief second you think you've been found out, they she takes a drink and you relax. She takes a long sip through the straw and then lays back down, relaxing in the sun. It occurs to you you have no idea how these work. You glance around, suddenly nervous that when this takes effect you may have company but you see nobody around.

You're looking around the garden when you hear the woman move. Glancing back at her you see her slowly walking towards you, a blank look on her face. She walks up to your chair and then kneels down with her hands in her lap.
...
...
It occurs to you that she may be waiting for instruction or a question or something...
"What's you name?"
"Melanie"
"Melanie, would you like to be my servant?"
"No" she blinks and a look of disgust flashes across her face before it goes blank again.
Hmm... "Melanie, you are my servant now, and will do everything I say."
She blinks but there's no emotion in her face this time. She is still for a few seconds then looks at you.
"Oh Sir, I'm so sorry, is there's something I can do for you? I didn't mean to be neglectful in my duties."
It seems you have to word things as a command or order if you want them to take affect.

"Melanie, you have been neglectful of your duties so..."