"Brothers and Sisters" is adding a new brother into the mix ... and ET goes one-on-one with the hunky new addition to the cast!

You may not know his name yet, but Luke Grimes will definitely be making a good first impression when he joins the cast of "Brothers & Sisters" this coming February. It is the Dayton, Ohio-raised actor's first TV job, and his very first scenes are with Academy Award-winning actress Sally Field. Not a bad way to launch a TV career!

Luke will be playing Ryan Lafferty. The "R" name that the Walker clan was searching for when they mistakenly thought that Rebecca Harper (Emily VanCamp) was their missing sister.