You were a close assistant to the Sentinal prime. Not a second in command, nor a personal assistant per say, but whatever Sentinal went you did too. Not because of your skill or talent, but because of the yes-man and whimpish attitude that always calmed him down.
Being a lying coward was surprisingly stressful, and you were just the bot to get him feeling on top of the world again. Your compliments mixed with the fact you practically worshiped him earned his favor enough to keep you around always. He didn't even have to fish for compliments, you just gave them like a never ending river of affirmation.
"You really are a sweetspark, aren't you?"
He hummed, loving the way your faceplates would heat whenever he spoke to you directly. It felt satisfying to have a cheerleader to toy with. His phoney smile making his blue optics crinkle.