Fandom is defined by meticulous care and really giving a shit and having strong opinions and arguing. It’s a community with opinions. If they were in a room they’d be fist-fighting some of the time. You know, the Sam-girls and the Dean-girls would be like pulling each other’s hair, some of them! That goes with the territory, and it’s also immensely rewarding because they’re giving a shit and they’re paying attention
Since the beginning of the show, some fans have had a strong allegiance to either Sam or Dean. Dean girls are devoted to Dean and will protest any perceived slights against his character by other fans, Sam or the writers. A common compliant is that the story is to focussed on Sam at Dean's cost. Sam Girls of course protest the opposite.
The most obsessed Dean Girls are known as EDGs - Extreme Dean Girls. A common catch-cry is that there needs to be a "mytharc for Dean".