It doesn’t matter to fans if Derek’s story has run its course and future plots would’ve been terrible. It doesn’t even matter that Patrick Dempsey wanted to leave Grey’s Anatomy. What matters is that these fans all had an intense connection to Derek, and especially to the relationship of Derek and Meredith, a relationship that has anchored the series from the beginning — after all, Grey’s Anatomy began with Der/Mer’s first hook-up before it even introduced the medical aspect of the show. Derek was characterized as a handsome, sensitive, and highly skilled surgeon, making his relationship with Meredith a desired pairing for fans. It’s the strong writing throughout Grey’s Anatomy‘s 11 seasons that built the connection that viewers felt to Derek, which is why it was so devastating when this connection was suddenly severed.
When it comes to most fandoms, audiences’ love for the characters often outlives the series itself. It can easily be argued that Grey’s Anatomy is past its prime — it can be argued that any show on its 11th season is past its prime — but it’s also clear that the Grey’s fandom shows no signs of slowing down. In fact, it gets more intense with each new season, as if to compensate for any less committed fans who have jumped ship, or at least to prove that there is still a huge demand for more Grey‘s and that they’ll keep watching as long as the show’s still on. But even that isn’t especially true; the majority of those who signed the petition claim that they will not watch Grey’s Anatomy as long as Derek remains, well, dead — showing that loyalty to a character can even supersede loyalty to the show that created him.