Janet is a beautiful young woman with long black hair and a bright smile.
Janet for the most part is only seen in flashbacks and shortly for that matter. She is first seen with a bright and welcoming smile for Dexter, and as he proclaims her...she is said to be a sweet person that looked at him in a way most did not. However, in a flashback regarding Joe Walker...she is shown to be fearful of her boyfriend at the time, who left evidence of abuse shown by bruising on her arms.
Three years before the reunion, she was said to have committed suicide due to depression or some other reason. This is however proven false, she sought divorce from Joe. Likely his attitude as well as the constant abuse became too much for her and she sought to divorce him for much of his assets in court. This, which would have ruined Joe, led to him shooting her and faking it as a suicide after a struggle between the two.
Janet Walker was born Janet McKellen and she went to Alan B. Shepard High with boyfriend Joe Walker and friend Dexter Morgan. She grew up with quite an academic career and was a popular student in class, with Dexter musing that, even though he didn't have friends in school, Janet was one of the few people to be nice to him. Both her and Joe eventually married and moved to Virginia. Three years before Dexter's 20th high school reunion she was found dead, an apparent suicide...that Dexter didn't believe due to blood in her fingernails likely from a struggle. Dexter, now seeking to prove Joe guilty, heads to the reunion with the intention of gathering a blood sample, analyzing and turning him into his next victim.
This plan has several drawbacks, first when he is distracted by various former classmates who have taken a new interest in him due to his looks and job as a blood spatter analyst, then by Joe himself when an attempt to gather a blood sample goes wrong (and he ends up pricking his own hand). Dexter then uses this opportunity to learn from Joe his feelings towards Janet, which reveal distaste hidden beneath a false caring for her passing...also hinting at the divorce. Dexter would later join a flag football signup, getting his opportunity to take a blood sample once more by elbowing Joe in the face and using a towel to gather the blood secretly. He is proven to be the killer in the end and Dexter lures him under the high school bleachers, learning of the divorce that caused him to kill Janet and growing sick of Joe's ramblings, ends her former husband's life with a sledgehammer to the face as well as a knife to his chest.