This Is Us: Out of All the Cassidy Theories, This One Makes the Most Sense

Like the series premiere, season four of This Is Us kicks off with storylines around a set of strangers. But by the end of the episode, these new characters ended up linked to the Pearson clan one way or another — the blind musician turns out to be Kate's son Jack, Malik becomes a romantic interest for Randall's adopted daughter Deja, and Cassidy, well, gives Nicky raised eyebrows (as one would) when he smashes a chair into her veterans' support group meeting. Played by Jennifer Morrison (Once Upon a Time and House), Cassidy Sharp is the most mysterious addition to the series so far. While we don't know how she fits into the story, here's why we're convinced that she's Uncle Nicky's daughter.

The first episode of season four starts Cassidy's story as she's a Marine stationed in the Middle East. Her return to the States is difficult, as she struggles to connect with her husband and son. When her husband brings up the cost of a water heater, Cassidy thinks back to her military experience and hits her son without thinking. An hour into the extended episode, she tells her story at a veterans' support group, explaining that she is separated from her husband, struggles with alcohol, and now drives an Uber.

And then, a crashing sound. It's Nicky, a troubled veteran himself, who sends a chair through the window, a bottle in his hand. As Nicky gets arrested, Cassidy carries the chair outside and gives him a strange look. But is it a knowing look?

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There's a possibility that Nicky and Cassidy are strangers who will later connect over their PTSD and addiction struggles . . . but that's not how the game usually works on This Is Us. As Kate's future son beautifully croons, "I found my way to you," it's easy to put two and two together and make the connection that the season will reveal Cassidy's fateful link to the Pearson clan, if she isn't a Pearson herself.

There's a strong possibility that Nicky might have an estranged daughter. Or, Nicky may have just discovered he has a daughter. Parents and children finding their way to each other? Sounds familiar: This Is Us begins with Randall tracking down William decades after his birth.

Reddit user emjaybe reminded us that Jack once visited Nicky, who told his big brother that he had a house before he moved into his trailer. It's possible, then, that Nicky also could have had a family. It's compelling evidence, considering that alcoholism, which Cassidy struggles with, is something that runs in the Pearson family (particularly Jack, Nicky, and Kevin).

There's speculation that Cassidy might be Kevin's future wife (as he has a son in the far future). But it seems like the connection is the strongest between Nicky and Cassidy thus far, given all those telling close-ups of them in the first episode. Dan Fogelman is a sly mastermind when it comes to emotional storytelling, so we'll have to wait and see what tricks he has up his sleeve.