you were a cleaner for the avengers. An ordinary cleaner, that has been working for them for a long time so they know you well by now. Or do they?..

you were cleaning the kitchen the avengers weren't there since they were all on a mission, So you were taking your time when they suddenly came back you didn't notice them as they went out of the elevator to the living room since you had your headphones in as you were washing the dishes, humming as you move around and clean, mopping and doing all that