Once again, no commentary from the SAB on chapters 42 or 43, and I'm not sure I have much to say either. Basically, Joseph is now in a position of authority, and he has a run-in with his (half-)brothers, who don't recognize him. They bow down before him, and he remembers the dream he had had about his brothers' sheaves of wheat bowing before his sheaf; no doubt this is the fulfillment of that dream. For whatever reason, (perhaps to get even?) he pretends not to know them, and makes things difficult for them, accusing them of being spies, throwing them into jail, and sending them back to Canaan with Simeon locked up in prison. He tells them that Simeon will not be released, nor will they get more supplies until they bring back Benjamin. (Possibly, Joseph is worried that they have killed Benjamin as they tried to kill him.) On the way back, they discover that their money has been restored to their sacks, and their father refuses to let them go back with Benjamin. This refusal is actually rather oddly insensitive, as Jacob's wording of the refusal is such that he is suggesting Benjamin is his only son, and he cares not for the fate of Simeon rotting away in an Egyptian prison, nor the nine other sons standing before him.
Eventually, though, they run out of food (although apparently not all kinds of food), and they have no choice but to go back. They decide that they dare not go back to Egypt without Benjamin and double the money they had brought before. When they get there, Joseph invites them to his house for lunch, which makes them suspicious. Certainly it's not customary for every foreigner that comes to Egypt looking for food to be invited to a meal with the viceroy of Egypt? Thinking it might be a chance to pull them aside and accuse them of stealing, they make sure to point out that they have brought back the money from last time. They are assured the money is of no consequence, and Joseph seats them around the room in order of their age, which surprises them since they still don't know he knows them. The author notes that the Egyptians, Joseph, and the brothers all eat in separate groups, as Egyptians find Hebrews to be an "abomination", perhaps a hint of what is to become of the relationship between them in the future.
Finally in chapter 44, they are sent on their way with provisions, but once again, they are given back their money, and Benjamin is given a silver cup as well. Joseph lets them get a head start, and then sends his servants after them to accuse them of stealing, but only the cup, which they are to claim Joseph uses for purposes of divination. (In Robert Alter's notes on 44:1, he points out that there is a sort of nightmare logic in this repeated returning of their money to them. After all, the great burden of guilt they carry is that they sold their brother into slavery in Egypt for some silver, and now they find that try as they might, they can't give their silver back to Egypt!)
The servants catch up to them and insist that they have stolen the "magical" cup. The SAB has issue with divination, and I would too, but there's no indication that Joseph really does perform divination with the cup, only that he wants his brothers to believe he does. The brothers are indignant, and certain that they are innocent, so much so that they insist that whoever holds the cup can be put to death, and the rest can be slaves. (This is another interesting allusion to their guilt over Joseph.) Joseph's servant accepts their claim of innocence, but suggests a lesser sentence: that only the person with the cup should become a slave, and the rest go free. The cup is found in Benjamin's sack, and the brothers are very distressed, because they know they can't possibly go back to Canaan without Benjamin. (Once again, this may be a testing on Joseph's part to see if his half-brothers will show any loyalty to his full brother.)
When they return to Joseph, Judah pleads that all of them ought to be put into slavery. Perhaps this because he knows there's no use going back without Benjamin, but it may also be because he realizes that it's himself and the other nine older brothers who have the real guilt here. Finally, Judah pleads that he himself would be taken, rather than the youngest, explaining the whole story of how Benjamin is his father's favorite child (Yes, as the SAB notes, Benjamin is not a "little" child or "lad", but an adult, however I think Judah is emphasizing the fact that Benjamin is the youngest, and thus the most vulnerable of the lot of them. I'm well into my thirties, and my mother occasionally refers to me as her "baby", somewhat to my wife's distaste.), and to go back without him would cause him to die of a broken heart. Judah, the brother who first suggested selling Joseph into slavery out of jealousy, now suggests that he himself should go into slavery to save his brother. As we will see in the next chapter, all of this finally becomes too much for Joseph.