
Gat and Cadence's unique relationship in We Were Liars was crucial to the overall storyline of the Prime Video series. Developed by Julie Plec and Carina Adly Mackenzie, the eight-episode mystery drama series revolves around the story of Cadence Sinclair Eastman (Emily Alyn Lind) as she pieces together fragments of her memory to remember what truly happened before she suffered a traumatic injury in her 16th summer in her wealthy family's beach house on their private island, Beechwood.
Aside from Cadence's recovery and unraveling of her past, the other liars in her inner circle—her two cousins, Mirren (Esther McGregor) and Johnny (Joseph Zada), and her childhood best friend, Gat (Shubham Maheshwari)—are at the center of the story of We Were Liars.
As the series progressed, Gat and Cadence forged a strong bond, which turned into something romantic that would completely change their lives forever.
Who Is Gat In We Were Liars?

Gat Patil is Cadence Sinclair's childhood best friend, who joined their annual summer trip to Beechwood since they were eight years old (aka Summer 8). While he is close with Mirren and Johnny, there is no denying that Gat has been joining their annual trip because of Cadence (his one true love). Fortunately, Cadence feels the same way, and she even describes him as "the boy who would change everything."
Gat and Cadence started to act on their feelings in Summer 16 (aka the summer of Cadence's life-changing accident in We Were Liars). Cadence noticed that Gat exhibited a different kind of aura and confidence she had never seen before, so she fell deeply in love with him. Eventually, the pair kissed, but this was Cadence's last memory before suffering a traumatic brain injury.
As she continued to piece together her memories, Cadence discovered that Gat has a girlfriend named Raquel Diaz, leading to their falling out. Despite that, the pair's strong feelings for each other prevailed. However, a year after Cadence's injury, Gat and the other liars were nowhere near her during her recovery.

After many twists and turns, We Were Liars' finale revealed what truly happened to the liars (minus Cadence). It turned out that Gat, Mirren, and Johnny all died in a fire that they started along with Cadence during one of the nights in Summer 16.
The liars burned down the Clairmont mansion (aka their grandfather's mansion) as a way to destroy the one thing that is tearing apart the Sinclair family. However, it backfired drastically when the incident killed three of the liars while Cadence suffered a lifelong traumatic injury.
While this death twist is a devastating blow to the viewers, there is still a silver lining, and it all boils down to Gat and Cadence's relationship in both summers (16 and 17).
Given that Gat is an outsider to the Sinclairs, it helps that he is the one who sometimes calls them out with their entitlement and overboard treatment of others. He knows social injustice when he sees it, and Cadence usually notices this whenever they are together.
By being together (whether as friends or lovers), Gat and Cadence's relationship is crucial in allowing Cadence to grow and make meaningful change within herself in We Were Liars.
Even after the reveal of Gat's death, a piece of him is still alive in Cadence after she forged her path by leaving her ties to the Sinclair family behind, due to her being tired of all the lies and manipulation.
How Are Gat and Cadence Related, Exactly?

Gat Patil and Cadence Sinclair Eastman are not related by blood, but their closeness grows beyond familial ties.
Cadence is part of a complex Sinclair family tree in We Were Liars. She is the daughter of Penny Sinclair and her husband, the granddaughter of Harris and Tipper Sinclair, and the niece of Bess and Carrie Sinclair.
Meanwhile, Gat Patil is an honorary Sinclair and an outsider to the family. He is Ed Patil's nephew (Ed is the boyfriend of Carrie Sinclair, Cadence's aunt, and Penny's sister). Gat became close to the family by joining their annual trip to Beechwood since Summer 8.
In We Were Liars, Gat and Cadence are each other's true love, and the pair's close bond defines Cadence's journey in the series.