Jennifer Jareau

Jennifer Jareau is a special agent that often acts as a liaison with police and media officials.

Background
JJ grew up in a small town. She graduated from East Allegheny High School near Pittsburgh, PA, where she was the captain of the varsity soccer team her senior year and earned an athletic scholarship to the University of Pittsburgh, it is also noted in Risky Business that she had a sister who committed suicide when she was young. And in Season Two it is stated that she has an 8 year old niece. She is a fully qualified federal agent, but has stated that she does not want to become a profiler.

Season One
Being the media/police liaison, Jennifer has spoken to the press many times in an effort to get the media to indirectly assist in investigations. She also assisted Hotch in getting information from serial killer Jacob Dawes. JJ once went on a date to a Washington Redskins game with Reid, but little has come of it romantically.

Season Two
During one case, she accidentally stumbled upon a barn full of dogs who were known to eat human flesh. Though she survived by shooting them all, the event left her with brief psychological scars. At one point while washing her hands, she hallucinated that one of the dogs was behind her, and almost shot Prentiss. She seems to have recovered in subsequent episodes. In the episode "North Mammon" in Season 2, after playing a key role in the case, she responds to Hotch's question about if she ever thought about becoming a profiler by saying that she likes being the voice on the end of the phone that the Detective or relatives of victims can talk to.

In the episode Jones she meets Detective William LaMontagne Jr. It is obvious they attracted to each other and at the end of the episode she gives him her number. Nothing appeared to have come to it until In Heat, when she finally showed him affection in front of the team. However, they had already known about the relationship from the beginning.

Season Three
In the episode Penelope, JJ shot Jason Clark Battle in front of FBI agents. The incident appeared to have little effect on her. In Heat revealed that she and William had been dating since Jones without her telling the rest of the team (although they had figured it out long earlier). It was revealed to the viewers in episode 3x18, The Crossing, that JJ was pregnant. New Orleans Detective William LaMontagne Jr is the father.

Season Four
JJ continued working during her pregnancy until Memoriam when she went into labor. She then went on maternity leave, her position being temporarily filled by Jordan Todd until she returned in Cold Comfort.