What does Genesis 43:18 mean?
Joseph's ten brothers are left to guess why this Egyptian ruler would order them all to be brought to his own home. After all, the last time they interacted with him, they were accused of being spies and were thrown in jail. Why would he now welcome them as guests? They still haven't realized this man is their own estranged brother (Genesis 42:8).Their fear is that this must be a plan to punish them—as they went home from the last trip, they discovered the money they'd paid for grain back in their bags (Genesis 42:26–28) for seeming to steal back the money they used to purchase grain on their previous visit. They did not steal it, of course. Joseph had it secretly returned to their sacks, along with the grain (Genesis 42:25). They have been fearful ever since discovering it that they were being set up to be accused of stealing. Now they assume the Egyptians will attack, enslave them, and steal all they have.
That the brothers fear being made "servants" is poetic justice: they are likely still associating their crime against their brother, Joseph, with what is happening to them now (Genesis 42:21–22). They seem worried God is finally punishing them for attacking Joseph all those years ago and selling him into slavery (Genesis 37:25–28).