I wouldn't worry about what everyone else is following at the moment. If you're into Merlin then you should just focus on that. I know there's quite a bit of fic out there and I'm sure there must be fandom communities. Speaking for myself, I tend to be pretty monogamous when it comes to fandoms. While I might be interested in a number of fandoms at the same time, I can only be actively involved with one. At the moment, that's BBC Sherlock.