The pattern that I've seen is that when a canonical het pairing is presented in such shows, the reaction by slash fans is very specifically negative towards that pairing.
I said that fandom tends to reserve the alpha male for the 'beta' male, and that when they don't, they'll slash him with someone else. I specified slash, which, on reflection, is incorrect. A 'secondary female' is often acceptable - as is the pairing of the main female character with a secondary male one. eg. Jack/Janet and Sam/Daniel - neither of which is as popular as Sam/Jack, but neither of which is quite as reviled, either.
The same fannish behaviour recurs with John/Teyla, Arthur/Gwen, and Spock/Uhura - you'll find more vitriol directed at these pairings within their fandoms than any other pairing.
And I picked these pairings and fandoms because they were the ones I was actually involved in, and so experienced these behaviours.
Interestingly, I can see John as bi-, where I have much more trouble with Jack. To me, Jack codes as 99% het - the exception is Teal'c. John, on the other hand, is bi- with Ronon, Radek, and Cameron Mitchell, but very specifically not with Rodney. The reason he and Rodney get on so well is because they're not at all attracted to each other. It means sex never gets in the way.
In SGA, Teyla's my little black dress, along with Ronon - they go with everyone. Oddly, in my head, they don't go with each other.
Re: From metafandom
I said that fandom tends to reserve the alpha male for the 'beta' male, and that when they don't, they'll slash him with someone else. I specified slash, which, on reflection, is incorrect. A 'secondary female' is often acceptable - as is the pairing of the main female character with a secondary male one. eg. Jack/Janet and Sam/Daniel - neither of which is as popular as Sam/Jack, but neither of which is quite as reviled, either.
The same fannish behaviour recurs with John/Teyla, Arthur/Gwen, and Spock/Uhura - you'll find more vitriol directed at these pairings within their fandoms than any other pairing.
And I picked these pairings and fandoms because they were the ones I was actually involved in, and so experienced these behaviours.
Interestingly, I can see John as bi-, where I have much more trouble with Jack. To me, Jack codes as 99% het - the exception is Teal'c. John, on the other hand, is bi- with Ronon, Radek, and Cameron Mitchell, but very specifically not with Rodney. The reason he and Rodney get on so well is because they're not at all attracted to each other. It means sex never gets in the way.
In SGA, Teyla's my little black dress, along with Ronon - they go with everyone. Oddly, in my head, they don't go with each other.