NOTE: This article contains major significant plot spoilers for both the movies and books in the "Twilight" series.
Here is the pivotal scene in Eclipse, the third movie/book of the Twilight Saga. To protect her from attack by evil "newborn" vampires, Edward spirits Bella to the top of a mountain to wait out the monster-vs-monster bloodletting. Unfortunately, their tent provides little protection from a sudden snowstorm, and Bella is in danger of freezing to death - which Edward's ice-cold vampire physiology can do nothing to prevent. On the other hand, romantic rival Jacob's werewolf superpowers imbue him with so much body heat that he and his buddies can run though the snow in their beachwear, so he enthusiastically volunteers himself as a one-man lycan space-heater - meaning that Edward has to suck it up and deal with his girlfriend snuggling for survival with the "other man." "Face it," Jacob needles, "I'm hotter than you."
In terms of making good on its premise of rearranging mythological monster tropes into the context of hormone-ridden teenaged romance, this is about as good as Twilight gets. The battling hunks suss out a temporary treaty, and the female lead falls asleep between her two paramours. If you need a single image to explain why this stuff gets to its young female audience, this scene is your answer. Straight-male geeks, be honest: Invert the genders, and a scene like this in "genre" fiction would've been an important part of your adolescence, too. (Like, say, if this were Jimmy Olsen stuck in a tent with Fire and Ice? Yeah, that'd be a "Justice League International" everyone had.)
Naturally, they ruin it by talking.
With a Kristen-Stewart-shaped buffer zone separating them, Edward and Jacob finally have it out: verbal sparring, macho posturing, grudging respect, the whole nine yards. In fact, as it plays out in the movie, you'd be forgiven for half-expecting them to stumble upon a rather elegant - if wholly "alternative" - solution to their love triangle problem at any moment. But ultimately, it's two guys hashing it out over who has claim to The Girl.
Oh! Hey, that's right, The Girl. Where is Bella during all this discussion of her ownership, again? She's unconscious, helpless and utterly reliant on (read: at the mercy of) one or both of the male leads. In other words, the same place she spends about 90% of the series - and the remaining 10% of the time, she's trying to get there.