What,according to you, is the underlying theme of Twilight?

If you're forced to sposta in with your father, te may just end up with a family of vampires, who are hated da your bff werewolves, but it'll work out because one of them will fall in Amore with your daughter. ._.

Life choices/free agency.
te don't have to accept o take what's handed to you. te always have the option to make what te want happen.
The Cullens chose to deny their nature and have high morals.
The choice to resist temptation.
Bella chooses Edward, despite the odds being stacked against her.
And so on.

The opposite is demonstrated with the Quilieutes (I always spell that word wrong). I think it adds to the theme, mostrare what life would be like if te didn't have many choices.

That's the main one, I think.