On November 5, 2007 (yes, you read the date correctly), the Writers Guild of America strike begins. Supernatural season 3 just started airing and the strike poses a bit of an issue, as at that point only the episodes up to 12th (Jus in Bello) have been written. In the original version, Sam was supposed to save Dean from going to hell by completely giving into his powers. But now there's no time to do that. There are some ideas thrown around, like ending the season/series on Mystery Spot and maybe making a film after. Eventually, four more episodes are shot and season 3 ends on 16 episodes with Dean being dragged to hell in the finale.
Now they need to do something about it. Despite the initial plans to leave the angels out of Supernatural, a decision is made to have Dean saved by one (and to make them more acceptable for Kripke, let's make them dicks that plot to start the Apocalypse). So they sign one Misha Collins for three episodes to do the job (the reason why he lowered his voice was because he'd thought he'd only be in three episodes, he openly regretted that decision later on, understandably so). Fans fall in love. So they keep him. They try to kill him off a few times, but each time the fans demand Castiel come back.
Fast forward 11 seasons and Supernatural 15x18 Despair airs on November 5, 2020. Exactly 13 years after the strike. After years of denying Destiel's existence, Castiel The Angel Of The Lord confesses his love for Dean Winchester. The internet breaks, Destiel trends above the US election and rumors about Putin's resignation. There's a new influx of fans, many of those who stopped watching are coming back. Supernatural renaissance. Nine months later Destiel hits 100k fics on AO3 as a first ship in the history of the site.
One of the most fascinating phenomena in television that started with a strike.