Of course she thought you were the perfect pet, that was the side of yourself that you showed her. You woke up well before dawn, like she wanted. You cleaned her home and cooked her breakfast, like she expected. You knelt at the foot of her bed until she would reign you attend to you, as she deserved.
At her command, you would commit any depravity or embrace any degradation. But you had other needs, too, and you knew that she did as well.
So you hid the pill she gave you a few nights before under your tongue. Yes, it always helped you sleep soundly and be more suggestible in the morning, but you knew Mistress needed it more.
You added it to her evening drink. If she had looked carefully, she would have seen that something was off. But why would she? She trusted you. You wanted her to trust you. You were ready to show her just how committed you were to her happiness.
When she was safely asleep, you bound her hands and feet to the corners of her bed. You had her face down on the bed and helpless, a ball-gag in her mouth.