She is played by Diora Baird.
Shannon is a social alcoholic due to her near-constant presence at bars and taking various men home with her. She is also possibly unemployed as she mentions that she was at one of these bars to get a job application - but when she is told there are some available, she does not want one. Shannon spends far more time bar-hopping and seducing men to get free meals from them, neglecting Robby not only directly, but also by failure to set any positive example. Even when Robby sets aside time to try and bond with her, Shannon leaves to go to happy hour anyway, blatantly stating her fear of being alone. Despite her many flaws, however, she did choose to raise Robby, unlike Johnny. However, Shannon appears to be at her wit's end with Robby, letting him do whatever he wants, claiming that there are no do-overs in life, and that it was too late for Johnny to try and mend his relationship with his son. She also viewed Johnny's attempts at getting back into his son's life as superficial, surmising that he probably only offered to get his son to move in with him so he could get out of paying for child support.
- Based on her personality, namely her neglectful behavior, obsessive need for companionship and risky behavior, it is very likely that Shannon suffers from Borderline Personality Disorder, a serious Cluster B mental disorder that results in unstable moods, behavior, self-image and relationships.