SES Erin Strauss was the BAU Section Chief, the direct superior to SSA Aaron Hotchner. Her job lay in administration, and she had little actual field experience. She appeared in Criminal Minds as a recurring character until Season Eight, where she was murdered by the Replicator. In Season Nine, her position was taken over by Mateo Cruz.
On Criminal Minds
Strauss seems to be under the impression that Hotch's team is disorganized and pose a threat to the BAU, prompting her to enlist Emily Prentiss to spy on the team (a maneuver that backfires when Prentiss, having become close to her team members, eventually resigns from her position) and to attempt Hotch's removal from the BAU with a pending investigation on his methods. She backs off her attention from the team after experiencing firsthand what the team lives with every case in the field, as seen in In Name and Blood, but not before making sure that they understand that none of them will ever be able to move up in any higher positions within the FBI (though this opinion appears to have been proven wrong in later episodes).
In episode 100, Strauss conducts the inquiry into the events surrounding the actual beating to death of George Foyet. She questions each team member to get to the bottom of the situation and ensure that "a bloodbath like this never happens again." She finally questions Hotch, who tells her that he believed if Foyet were allowed to get up off of the floor, he would have killed Jack too. She effectively clears him saying, "That's good enough for me." She also falls away from her cold and spiteful personality that was the norm for most previous episodes and sincerely tells Hotch how sorry she is and that "if there is anything you [Hotch] or your son need..." she will help.
In the episode Self-Fulfilling Prophecy, it is revealed that Strauss is fighting alcoholism and that Hotch knew that she was getting help. However, it seems that she had relapsed as she tried to keep it a secret. In the end, Hotch and Morgan arranged for her to be checked in privately. In the Season Seven two-part finale Hit and Run, she is hired to supervise the hostage situation at the Colonial Liberty Bank perpetrated by the infamous Face Cards. Hotch convinces her to delay the Director's order for SWAT teams to move in. By the end of Run, she thanks Morgan for finding out about her drinking problem and even jokes to him that Morgan won't be happy when she returns to duty when he states it will be an honor to have her back, possibly her first instance at displaying humor to the team. She is present at JJ and Will's wedding and happily dances with Rossi and the team, showing that she might have become a better person towards them.
Strauss becomes more prominent in Season Eight. It is revealed in The Silencer that the newest member of the BAU team, Alex Blake, worked with her during the Amerithrax case, during which Strauss left her to take the fall when a linguistics flub led to the arrest of the wrong suspect. As a result, Blake didn't get along with her afterward. At the end of The Silencer, Strauss tries apologizing to her, but she is turned down. In Carbon Copy, she specifically oversees the investigation into the Replicator, and by the end of the episode, she apologizes to Blake again, and this time, her apology is accepted. In Brothers Hotchner, she is abducted by the Replicator, later revealed to be a disgruntled FBI agent named John Curtis, whom she left to take the blame along with Blake following the Amerithrax case. In The Replicator, Curtis poisons her with spiked wine and leaves her to die. She is found on the streets by Hotch, and she admits that the Replicator forced her at gunpoint to drink again. She dies in Hotch's arms after begging him to stay with her as she doesn't want to die alone. Strauss indirectly helps defeat Curtis post-mortem when Rossi uses her sobriety chip to escape his trap, leaving him to apparently die in an explosion. After her funeral, the team celebrates her life during dinner at Rossi's garden, discussing happy stories of her time with them and acknowledging her as a good woman, friend, and mother.
In the episode Hit, it is implied that she and Rossi had spent the night together in a hotel. In Season Eight, more and more hints are given that they are indeed in a romantic relationship, and in Brothers Hotchner and The Replicator, neither of them attempts to hide it. The way Rossi grieved over her death and the fact that he knew her children were the last pieces of proof of their relationship.
Starting with the Season Nine episode To Bear Witness, her position is now occupied by Mateo Cruz. She reappeared in 200 in a flashback scene with JJ and Cruz talking about an assignment by Undersecretary Rosemary Jackson.
Initially being an antagonist towards the team, Strauss's opinion of the BAU progressively changes due to her experiences in the field during the episode In Name and Blood and seeing the aftermath of the events in 100. She appeared to be very disturbed while reading the autopsy report on Haley and determined that Hotch was justified in killing Foyet. She also expresses concern for Hotch in 25 to Life and was glad he is taking some time off. It is then shown in the episode The Stranger that all of the animosity with the BAU she had once held had vanished when Strauss told Hotch that his team had dealt with terrible things in one year, namely the "death" of Emily Prentiss and the events surrounding Foyet, but that they had dealt with them exceptionally. She also told Hotch that she was taking some time off due to reasons that are believed to be personal (later revealed to be her alcoholism) and that she wanted him to take care of the departments under her responsibility while she was absent. Through Season Three to Season Five, Strauss changes from being an antagonist to the team to a woman that understands the difficulties that the team goes through and has started to respect them. In About Face, she apparently doesn't believe people can be selfless.
It is revealed that she is an alcoholic in Self-Fulfilling Prophecy, something that ruined her relationship with her children. By the time of her death in The Replicator, she is over a year sober and a sponsor to other struggling alcoholics, having developed a strong animosity for alcohol, but is forced to drink again before she dies at the hands of the Replicator, the alcohol she drank having been poisoned by him.
- Though Strauss is stated to have little field experience, Morgan told the team after her death that she was an excellent shooter. It is possible that she just never fired a gun while on the job, or he was referring to something else entirely ("The Replicator"). It is possible that, prior to her death, Strauss may have recently spent time at the shooting ranges, where Morgan may have seen her skill with a firearm.
- Strauss's FBI database username was "Strauss_E_218" ("The Replicator").
- Season Two
- Season Three
- Season Five
- Season Six
- Season Seven
- Season Eight
- Season Nine
- "200" (via flashbacks)