Yosef, who correctly interprets several dreams throughout this story, interprets his own dreams as foreseeing his seminal role in leading the family in preparation for the long and difficult period that lay ahead.
Parashat Miketz tells of Yosef's harsh treatment of his brothers when they come to purchase grain from Egypt due to the famine that had struck Canaan. Yosef serves as the Egyptian viceroy and oversees the sale and distribution of the enormous quantities of grain that the country had stored during the previous seven years of surplus. The brothers, therefore, obviously do not recognize him. Yosef accuses his brothers of coming to spy the land and demands that they bring him their younger brother, Binyamin, as proof of their family background.
The fundamental question that has been addressed concerning this parasha is, quite simply, what is Yosef's objective in all this? Why does he find it necessary to torment his brothers - not to mention his father - who are already languishing from hunger? Why is it so important that Binyamin join him in Egypt?
Among the more famous explanations offered to explain Yosef's conduct is that of Abarbanel and Rav Yitzchak Arama (the "Akeidat Yitzchak"), who suggest that Yosef seeks to lead his brothers to complete repentance for their crime. The brothers had resented Yaakov's preferential treatment towards Yosef, as the son of his favorite wife, Rachel, and therefore decided to eliminate him. Now, Yosef devises a plan by which he places them in a situation where they have no choice but to commit themselves to the safety and protection of Binyamin - Rachel's other son, who, after Yosef's alleged death, had taken Yosef's place as Yaakov's preferred son. The famine that ravages Canaan affords Yosef the opportunity to force their brothers to treat Binyamin kindly and disregard his preferred status at home. Many years earlier, Yosef and his brothers were alone and they sold him into slavery; by the end of our story, Yehuda - the one who suggested selling Yosef - offers to remain in Egypt permanently as a slave in order to allow Binyamin's safe return to his father in Canaan.
The Ramban employs a similar approach in explaining the final stage of Yosef's plot, when he has his goblet placed in Binyamin's bag to frame him as a thief. According to the Ramban, Yosef wanted to ensure that the brothers harbor no ill will towards Binyamin as they had towards him. The hiding of the goblet thus served to test the brothers' loyalty to their youngest brother, to see if they would indifferently return home and let Binyamin remain as a slave in Egypt, or if they would exert themselves on his behalf. (As we will see a bit later, the Ramban adopts a different approach in explaining the first stage of Yosef's scheme - the demand that the brothers bring Binyamin to Egypt.)
The obvious question arises, what right did Yosef have to cause his brothers - not to mention his father - so much grief and anguish in order to lead them along the path of teshuva? Is anybody entitled to play the role of God and torment his fellow in order to cause him to repent?
Rav Soloveitchik zt"l (see http://shamash.org/listarchives/mj-ravtorah/miketz.96.ravtorah.96) explained Yosef's conduct by focusing on his initial response upon realizing that his brothers stood before him: "Yosef remembered the dreams that he had dreamt about them… " (42:9). The Torah here indicates that this situation reminded Yosef of his childhood dreams of leadership and authority over his brothers (see 37:5-9). Indeed, the Ramban claims that Yosef's scheme was motivated by these dreams, which he felt obligated to bring to fruition, thus necessitating that all his brothers - including Binyamin - come to Egypt and bow before him. But according to the approach of Abarbanel and Akeidat Yitzchak, that Yosef's aim is to lead his brothers to teshuva, of what relevance are his dreams to his scheme? Rav Soloveitchik explains that Yosef's dreams gave him the right - and the obligation - to ensure his brother's repentance. After all, what did the dreams mean? They meant that Yosef was to serve as the family's leader in preparation for the long and bitter exile that awaited them. Yosef understood the long-term implications of the current situation. The unbearable conditions in Canaan, the fact that Egypt was the only source of sustenance for the inhabitants of Canaan, and Yosef's position of authority in Egypt, all led to the inescapable conclusion that Yaakov and his sons must now settle in Egypt and begin an era of exile. This era, Yosef correctly realized, could not begin with a rupture between Yaakov's sons. If Yaakov's children are to retain their identity and preserve their tradition and heritage in Egypt, they must work together, rather than harbor mutual feelings of resentment and animosity.
Yosef, who correctly interprets several dreams throughout this story, interprets his own dreams as foreseeing his seminal role in leading the family in preparation for the long and difficult period that lay ahead. Rightfully so, then, he assumes the right and the responsibility to guarantee that his brothers will feel genuine remorse for their mistreatment of him, so that the twelve sons of Yaakov can come together once again and join forces to withstand the years of hardship and suffering that await them.