You know, I've read a ton of 'Twilight' fic over the years, and I think Bella/Alice is one of the most consistently fascinating dynamics, not because it's inherently romantic, but because it pulls apart the canon and asks different questions. It's less about the love triangle and more about intimacy built on foresight and choice. Alice sees Bella's future, all the messy, mortal, dangerous paths, and chooses to walk beside her anyway, even when it defies the clan's logic. That's a powerful friendship foundation. Then you add the rivalry angle, which often gets twisted into something deliciously bitter—Alice knowing what's best for Bella versus Bella's own stubborn free will. I've seen fics where they're competing for Jasper's attention in a twisted ménage, or where Alice's visions create a self-fulfilling prophecy of envy. The best ones make the rivalry feel like the flip side of their devotion; they fight because they care so intensely, not because they hate each other. It turns the 'perfect, happy Cullen family' image inside out, and that's where the real story lives.
I stumbled on a crossover once where Alice was a time-traveler trying to prevent Bella's death in every loop, and the rivalry became this cosmic frustration—Bella refusing to be saved, Alice refusing to give up. That stuck with me more than a lot of the straight-up romance plots.