Disclaimer: I don't own anything to do with the actors mentioned.
Opinion:
Brian is a troublemaker in Debbie's opinion. He's no good for her easily influenced son.
She knows he drinks, she suspects he smokes, while her son's into comic books. The only good thing Brian is into is soccer. He also likes old movies, anything Dean or Brando, sometimes Grant, Kelly and others. He watches them hungrily from her couch, Michael nestled in his arms. It's the only time she ever sees him still.
Sometimes when he thinks she's not watching she catches him looking at Michael instead of the screen. Then, just then, she thinks maybe she's wrong about him.