Is there a misprint in the Adventure? Vella is meant to have a sidebar, but she does not (page 10) She does have a breakout box telling you a bit about her and next to her entry is a sidebar for the Troll, but not for Vella. In essence, what is the reward for rescuing her? Her small section does hint she knows something about the layout - is this meant to be the reward?
...
I think that if you leave her to die, you'll receive a Shadow Point, maybe even two, at the end of the adventure (since it's just one event among many, the Shadow Point will be given if the players are aware they let someone die). This is just a suggestion, but it's a good one.
Arthur.