Why does Jacob spend the night at Hank's in Chapter Five? What agreement does he come to with Hank?

They return to Hank's where Sarah is making lasagna for supper, and Jacob agrees to stay. Jacob and Hank drink a lot of wine, and Jacob winds up spending the night. Before going to bed, Jacob tells Hank he'll help with Lou if Hank will help Jacob secure the farm for his own. Jacob agrees but knows that he won't really.