fannish confusion

So I've signed on to a bunch of Sherlock BBC comms, but I'm still signed on to a bunch of SGA comms as well. And inevitably, as I'm skimming down my f'list, I'll start reading a fic summary about "John," and halfway through (typically when it refers Rodney or Sherlock) I'll realize I was thinking it was the other fandom, and it's always a bit disorienting (or disorientating, I suppose, depending which fandom it is).