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Mary Louise's Backstory On 'Big Little Lies' Was Finally Revealed

All season long, the conflict between Big Little Lies' Celeste and her mother-in-law Mary Louise has titillated viewers of the HBO hit. As fans have watched the Season 2 newcomer intimidate the Monterey Five (with tactics that include that unforgettable guttural scream), they have grown more and more curious about what makes her tick. Mary Louise's backstory on Big Little Lies was finally revealed in the Season 2 finale, and it all makes so much sense.

Spoiler alert: Spoilers for the Season 2 finale of Big Little Lies follow. Throughout Season 2, Mary Louise Wright (Meryl Streep) played antagonist to Celeste (Nicole Kidman) following the death of Perry, Mary Louise's son and Celeste's husband. At the start of the season, Mary Louise's mission appeared to be to get to the bottom of the mysterious circumstances surrounding her son's death. However, midway through the season, Mary Louise appeared to change course; instead of playing detective, she switched her laser focus onto Celeste and Perry's twin boys, Max and Josh.

Citing Celeste's erratic and self-destructive behavior following the death of Perry, Mary Louise petitioned the court to gain custody of the children, much to the despair and enragement of Celeste. Though she admitted that she had been struggling because of the death of her husband (and her role in covering up the real reason why he died), Celeste was adamant she was still fit to parent her boys, and was not going to let her malicious mother-in-law take them away from her. Anyone keeping up with the season knew some stuff was going to go down in the courtroom for the finale.

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And that it did. When Mary Louise took the stand to be questioned by Celeste, fans awaited with bated breath to see how the showdown would play out. Celeste started off fairly predictably, asking Mary Louise about her observations since coming to Monterey. But then she really dug in. After Mary Louise brought up a moment in which Celeste pushed her son when losing her temper, Celeste fired back: “Did you ever lose your temper with your boys?” That's when it all came out.

"Did you ever lose your temper while driving an automobile and cause the car to crash?" Celeste asked Mary Louis, with such intensity I truly felt shook to my core. "Your son Raymond died in part because you lost your temper. Isn't that true?"

Bombshell, dropped. Following the revelation, Celeste announced that Perry had confided in Celeste about the accident, and how he was treated after it. Though Mary Louise claimed she took care of Perry following the tragic occurrence, it also became clear that she blamed him for it. Though there is no excuse for how he behaved as an adult, the abuse Perry endured from his mother as a child could have had a major effect on the man he eventually became.

With one brief interrogation, all of the questions about Perry's mysterious brother were answered. And it turns out, those answers had a lot of bearing on Celeste's fight for custody of her children; by the end of the proceedings, Celeste won, and was able to keep her boys away from her devastated mother in law, and hopefully allowing her to move on from her harrowing experiences.