As a First Assistant Director, your working relationship with the Director is going to be one of the most important relationships you will have with anyone in this business. You always have to keep in mind the “industry politics” of the situation: is this a movie you are working on, or is it a TV Series?
Directors interview and hire the First Assistant Director on a feature film (and TV Movies) while the Production Manager (or Producer) hire the First Assistant Director on a TV Series. Therefore, you always need to look at this difference from the point of view of your relationship with the Director:
In Television: The 1st AD works WITH the Director, FOR the Producer
In Features: The 1st AD works FOR the Director, WITH the Producer