You know, of BBC had replaced either John or Sherlock with a female, people wouldn’t be able to even deny that there is some chemistry between them. But because they’re both men, people are denying the chemistry, because it’s not very “traditional” so romance doesn’t jump out at them. But if one of them were female, all the script and scenes would be very obviously romantic.

If one of those two was a woman, ‘some chemistry’ would not be the phrase.  People would have started hollering about the astounding sexual tension after the first episode. and predicting that they’d be in the sack by the end of season 2.

But let’s not blind ourselves.  The press DID do that.  I’ve seen more articles that refer to the sexual tension between the two of them than ones that don’t.  The chemistry IS strong enough to carry through despite them being two men.  If one of them was a woman, TV Guide would be declaring that Sherlock is the next Moonlighting.  

The possibility that they wouldn’t is what wouldn’t exist in that case.  As men, there’s a strong sense among the viewership—both casual fans and professional critics (not to mention professional fans 😉 )—that they could be going in that direction.  If one of them was a woman, the idea that they weren’t going in that direction would be unthinkable.

(Which, as it happens, is one of the things that catastrophically pisses me off about canon het ships.  It’s even more impossible for there not to be one than it is for two men to get together.)