Mary Louise is more than just a meddling mother-in-law, that's for sure.

Meryl Streep Big Little Lies
Credit: HBO

It’s been two weeks since HBO’s critically acclaimed series Big Little Lies returned to the small screen and with it came a major casting addition: Meryl Streep. The Hollywood icon steps into Monterey as the grief-stricken mother of Perry (Alexander Skarsgård) who was dearly departed down a flight of stairs at the end of season 1. But what does her arrival mean for the newly minted Monterey Five?

The internet is already ablaze with fan theories about what will happen in the aftermath of Perry’s death during the season one finale. While those theories heavily surround Zoe Kravitz’s character Bonnie’s potential PTSD related to her role in Perry’s death, it’s Mary Louise’s arrival and hunger for answers that has fans wondering if Meryl Streep-with-fake-teeth will be the key to the friend group’s undoing.

It would be a gross misuse of Streep’s talent to cast her as nothing more than a meddling mother-in-law. Even though Big Little Lies has possibly the most star-studded ensemble cast to ever ensemble, well, nobody puts Meryl in a corner. As Oprah Magazine pointed out (via a Reddit user), the show’s promotional poster has letters from the title covering everyone’s mouths except for Streep’s (as Mary Louise). This could mean that she’s got some big talking to do, which we’ve already seen in the way she confronts Reese Witherspoon’s character.

When we first meet Mary Louise, she seems rather unassuming, even quiet. Then, just as quickly, when Madeline Mackenzie (Witherspoon) approaches Mary Louise at the coffee shop, she becomes someone else. She’s rude and frigid, telling Madeline that she “finds little people to be untrustworthy.” She then bizarrely says that she prides herself on being a good judge of character — bizarre for viewers and Madeline, who know her son to have been an abusive husband and violent rapist. This leads us to fan theory number one.

Theory 1: Mary Louise is an abuser herself.

The unfriendly way she speaks to Madeline so casually after hardly knowing her is concerning. She treats a woman she barely knows with unnerving disrespect, saying, “I want to know what happened that night. And I’m very tempted to ask you, but I doubt I would get the truth, would I?” When her daughter-in-law Celeste (Nicole Kidman) walks up, Mary Louise acts as if the exchange hadn’t been heated at all — an early red flag of the gaslighting behavior she’ll continue into the second episode.

Later in the premiere, Madeline finds Mary Louise consulting with a real estate agent at her office, and Streep’s character again changes her tone to be sweet in front of Madeline’s co-worker. When they’re alone, she tells her she reminds her of an “utterly vapid” friend she used to have. This echoes the way Perry would speak down to Celeste when they were alone, but much more lightly when they were in the presence of others.

In the first episode, Mary Louise makes undercutting comments to Celeste about the amount of fast food her boys eat, but then is as saccharine sweet as any Grandma could be when she’s with the boys herself. When Celeste stops the boys from fighting moments later, she says to Mary Louise that they’re still recovering after their father’s death. Mary Louise says, “Well, they’re grieving, Celeste. Their father’s death is not something to be recovered from like a cold,” belittling her in the same way Perry did when they dropped the boys off for the first day of school in season one.

By the second episode, Celeste confronts Mary Louise about her treatment toward Madeline, coming to her friend’s defense (she says Madeline once saved her son from drowning; without skipping a beat, Streep hisses, “where were you?” turning the conversation, again, to a Celeste shortcoming). Mary Louise admits to not liking Madeline, as a way to seed doubt into Celeste’s mind about her friendship, again mimicking a Perry-ism. In the same episode we see a flashback of Celeste’s late husband telling her he’s glad she has no living family, so he can have her all to himself. Isolating somebody, causing distance between their trusted confidantes, is a classic example of controlling, abusive behavior.

The similarities in their speech are enough for suspicion, but her bizarre praise and belief that her son was incapable of causing harm to his wife, unless duly provoked, would point to the fact that she, too, ruled with an iron fist — and felt justified in whatever result that led to — and that Perry was merely emulating his upbringing. To that point: Mary Louise also brings up Perry’s twin brother, whom we learned in season 1 died in “an accident” when he was five. Did mother and son have something to do with that? Maybe we'll find out this season.

Theory 2: She is a survivor of abuse — and the voice of Celeste's inner conflict.

Maybe she wasn’t the abuser. Perhaps, instead, she was the abused. Perry’s behavior seems chronic and severe enough to have been founded in a traumatic childhood of his own. This theory is that Mary Louise’s husband was possessive and abusive toward her, and perhaps their sons as well. Self-preservation in that kind of situation could’ve taught Perry to compartmentalize the two sides of his personality and, similarly, how Mary Louise learned to switch between the two sides of herself. The nervous fidgeting with her cross necklace could be an anxiety response, for that matter.

When Celeste returns to counseling and discusses the aftermath of what happened that night, she admits to feeling conflicted about the whole situation. Perry had still been her husband, after all. She says she feels guilty for that night, as if it was somehow partially her fault that he had fallen to his death — if she had left him sooner, or if she hadn’t said anything to set him off, he might still be around.

These feelings are intensified with Mary Louise, as she says, "underfoot." Instead of seeing the bad in her son, she talks only of his positive attributes. He was a good son, a good father, a good husband, and he took care of everyone. In the first episode, she talks to her grandsons about how the sons of her friends couldn’t even come close to how amazing Perry was. He was funny, he was handsome, he was a provider, she says. She tells Celeste he couldn’t be an abuser. He couldn’t have been a rapist. And if he was any of those things, well, he must have had a good reason to be that way — as if she had been trained to rewrite history in this way herself.

This sort of toxic dialogue could be getting into Celeste’s head and making her think that if she hadn’t been weak, if she hadn’t given him a "reason" to abuse her, then none of this would have happened. And that brings us to a theory about why Meryl Streep’s character would want to undercut her daughter-in-law’s self-confidence as a parent.

Theory 3: Mary Louise will attempt to get custody of Celeste’s twins.

When Celeste is telling Max and Josh about Ziggy (Shailene Woodley’s son) being their brother, they ask if their dad was a bad person. She says no, that “He was a beautiful, wonderful man.” Was Celeste trying to sugarcoat the situation and hide the man he really was from their children, or is it something that she says because she believes that she herself caused his abusive outbursts? The latter certainly seems like what Mary Louise believes — or at least what she wants Celeste to believe about herself. The reason for that could be that she's attempting to establish Celeste as unfit to be the boys’ mother. Perhaps she’s swooped into town not to help Celeste take care of her boys, but to take Max and Josh away from her. One could see her wishing to have another shot at raising twin boys, since there was a tragedy with one of hers, and the other grew up and left her — for Celeste, the "enigma" Mary Louise just can't crack.

Theory 4: Mary Louise will drown herself when she learns the truth about Perry.

Maybe she wasn’t the abuser. Maybe she isn’t there just to send Celeste spiraling. Maybe, just maybe, she is an unassuming mother who doesn’t know the truth about her son, can't accept it when she first hears, and truly finding out will destroy her. When Mary Louise learns of Perry raping Jane in the second episode, she implores Celeste to desperately try to disbelieve Jane’s claim, saying Perry “wasn’t capable of doing the things she said. He wasn’t. I’ll never believe that.” Celeste then tells her that he was never innocent, that he consistently beat her, but Mary Louise refuses to believe that, too. She seems pained by any stain on her son’s memory.

As another user pointed out on Reddit that Bonnie’s mother has a vision in the second episode of someone drowning, and that by the end of the season, it might be Mary Louise. During their exchange about Jane and Ziggy, she tells Celeste that she’s going to the cops with all of the information that the Monterey Five had left out: that he had fathered another child from Jane, that Celeste was planning to take the boys and move into another apartment, that she only learned of Perry’s infidelity mere moments before he fell to his death.

At this point, it seems like she doesn’t believe a word Celeste says against Perry, and is trying to build a case against her. When she sees the facts truly align against her son, meaning the second of her twin boys was lost to tragedy (including the tragedy of bringing violence and harm to other people), it may be too much for her to bear. Last season showed Shailene Woodley's Jane running straight off a Monterey Cliff, again and again, as if in a dream. Perhaps, this season, someone else will.

One thing we know for sure is that Meryl Streep has viewers on their toes each time she twirls her cross necklace or puckers her mouth around the prosthetic teeth that make this character’s face so different from her own. What comes out of her mouth next is anyone's guess.