What long-lost secret twist have the Rick and Morty writers been keeping under wraps for the past four seasons?

Rick and Morty Season 4 is back, promising more dark adventures for Rick Sanchez, Morty Smith, Jerry, Beth, Summer, Meeseeks, and the rest. But ever since Rick and Morty Season 1, the writers have hinted at a mysterious secret that they wanted to save for the Rick and Morty final episode... and that a random Redditor deciphered it! Still, they've refused to reveal what the twist was. In this episode of #BigQuestion, Filup Molina and Erik Voss speculate on what this secret plot could be, based on clues hinted throughout the series. Are Morty and Rick the same person? How aware is Rick that he exists in a TV show? What is the secret truth of the Mega Seed that Morty and Rick sought in the Rick and Morty first episode?