At the end of the quest, a few things came to my mind.
1 - During the quest, Vala says the monsters like her kind for are enough. it means she knows Corpus is a bunch of rotten people and can't do anything about it or does not care. In the movie Die Hard: with a vengeance, the villain says something similar.
2 - When Parvos extends his hand, it is not kindness. It's a deal. And i don't think he will demand money. I think he will ask for a piece of her soul. Not literally, but the things she will have to do to pay for the favor...they will eat her soul, i'm sure.
Isn't this kind