Vin Looks over Elend at Night, then Zane Arrives
So Vin makes her decision here. Yes, she's been manipulated. But, as Breeze is fond of saying, we all manipulate each other all of the time. Zane didn't get her to do anything that she didn't already lean toward doing.
That said, Zane IS a master at manipulating people. I wanted him to be brilliant at playing with people's emotions. He's been Soothing and Rioting Vin for most of this book, but only very subtly. You rarely get to see that explicitly, since when it's happening, we're in her head and her emotions just feel like emotions to her. But watch the narrative and you'll see little spikes of emotion caused by Zane.
Even without emotional Allomancy, however, I hope that you can see why Vin made the decision that she did. It's important for me, and this book, that she does what she does next. She had to try the violent way. She had to give in, I think. It was always there, hovering so close to her, that if she'd rejected it without ever trying, I think it would have felt like a worthless rejection.
Now, however, the danger with tasting Zane's way is that she'll give in completely.