Got an idea for you, variable emotions/moods for the robot.
Incontinent Cell
Basic idea would be to have the robot run a calibration test for simulated emotions.
During this time everything starts out from 0. Emotions could go from -100 to 100.
Emotions could be, happiness, lust, love, etc with their opposites.
The MC would have to induce all emotions in the robot by increasing/decreasing those emotion values, after all have been calibrated to all possible emotions the MC can configure the robot's personality and have it on set values or dynamically changing.
The emotions would influence how the robot acts, from being nice and loving to tsundere to completely hating and anything else you can imagine.
Of course there should be an in-built failsafe preventing full sentience or harming the MC/Owner on the robot. MC could choose to remove it further progressing the storyline or potentially having the robot kill him for pissing her off or neglecting her.