Warning: The following post contains spoilers about season 2 of 13 Reasons Why.
In episode five of 13 Reasons Why, Clay (Dylan Minnette) sees a postcard from Justin (Brandon Flynn) to Jessica (Alisha Boe) that says "To Nancy, I’ll always love you. Sid." The postcard is key because it leads Clay to find Justin, who's been living on the streets of Oakland. The card also lets us know that Jessica and Justin aren't over. Jessica keeps the postcard on her mirror — clearly, it's not over. They're still not over!
A little background, here. First of all, Justin and Jessica have a history with these names. In season 1, they dressed as Sid and Nancy for Halloween. At school, Justin and Jessica present Clay with their costumes, asking, "Clay gets it, right?"
To which, he responds, "Yes. Sid Vicious, born John Ritchie, bassist for the Sex Pistols, and his girlfriend Nancy Spungen."
This is not information Clay should have on hand, really, considering his age. But it's awful convenient for the 13 Reasons Why writers to have a character dish out this info. (The likelihood that most viewers know who Sid and Nancy are is slim.)
Sid Vicious and Nancy Spungen's names have become a pop culture symbol of toxic couplehood. Vicious, born Ritchie, as Clay said, had a famously troubled relationship with Spungen. "Troubled" is putting it lightly — Spungen died of a stab wound to the abdomen when she was 20 years old. Vicious was the primary suspect in her murder, but he died four months after her death of a drug overdose. Which is why Clay responds, "You know how it ends, right?"
Justin and Jessica will likely have a better ending, although, with 13 Reasons Why, you never know. Season 2 sees Justin addicted to opiods while Jessica struggles with intimacy. Jessica dabbles in a relationship with Alex (Miles Heizer) and Justin does his best to win her back. Spoiler alert — he does, at the eleventh hour, to the tune of "Back To You" by Selena Gomez. This version of Sid and Nancy is a lot tidier than the original.