How can an author so totally get a relationship in one fandom her works are practically emblematic for the pairing, and in another fandom depict another relationship in such a way that any interaction between the characters rings with a dissonant, jarring sound of total wrongness?

In one fandom, her stories show the love between the protagonists so clearly that it seems imbued in every line, whereas in the other there's such a latent... I don't know, callousness? Banked aggression? Unexpressed hostility? lurking behind every word she has the men in question exchange - which is entirely out of character (according to both canon and fanon). It made me so uncomfortable, I had to stop reading (whereas I have almost all of her stories in the first fandom saved to disk, for I love reading and re-reading them).

It's not like the author had to explore the second relationship in a vacuum; to the contrary, she was far from the first prolific and dedicated writer in it; her stories are just a drop in a pre-existing, vast ocean featuring a commonly shared, different view of the characters' relationship across the majority of the fandom^*.

So I just can't help going "huh?". What causes something like this? Is the author standing on her head?!

Or to channel Rodney McKay: "She's wrong, wrong, wrong!"

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^* Not that the majority shaping and creating fanon in a specific fandom is always right - far from it. But here, I have to say, I am sticking with the mainstream.