Please continue to have Rabbi Hoffman in mind in your prayers for a complete & speedy recovery, among the ill of the nation.
Setting the Stage
By Rabbi Joshua (dramatically known as the Hoffer) Hoffman
The Talmud (Shabbos 12) tells us that a father should never favor one son over another, because as a result of the two measures of silk by which Yaakov favored Yosef, our ancestors ended up in Egypt. This passage is a bit difficult, because exile was already foretold at the bris ben habesarim, many years before. The Netziv explains simply that the favoritism Yaakov showed would have been enough on its own to cause the exile.
Rav Yosef Dov Soloveitchik zt"l, however, based on a midrash cited in the Torah Shleima, took the gemara in a non-literal way. The Rabbis tell us that Yaakov sought to sit in tranquility, but the trouble with Yosef arose. What this means is that he wanted Mashiach to come, and he could have. Just as the 210 years the Jews spent in Egypt were considered as 400 years, so too, the 20 years Yaakov spent with Lavan could have been considered as 400 years. The only reason that didn't happen is that the brothers did not appreciate the principle of how good and pleasant it is for brothers to dwell together. As representatives of G-d in the world, the nation had to be unified,reflecting the Unity of G-d. The Midrash in fact says that Yehudah went down from his brothers, Yosef went down to Mitzrayim, and Yaakov mourned. And G-d was busy sowing the seeds of Mashiach. The conflict of the brothers necessitated the preparation for the path of Mashiach.
This conflict then had to be resolved in order for redemption to come. We find at the end of Parshas Vayechi that the brothers, speaking in the name of their departed father, asked Yosef for forgiveness.
Interestingly, Rabbeinu Bachya notes that we never find explicitly that Yosef did indeed forgive his brothers. Why not? Perhaps Yosef believed that the brothers first needed to forgive themselves and not become mired in a black sheep complex, thinking they could never change. As my teacher, Rav Aharon Soloveichik zt"l explained, that is why he put them in a situation in which they had to save Binyamin, to convince them that given the chance they would not repeat the same mistake as they did with Yosef.
I believe that the symbiotic relationship between Moshe and Aharon, as displayed in the book of Shemos, served as a further impetus to the tribes, setting up a model of brotherly love, with Aharon wholeheartedly accepting his younger brother as his successor in leading the people to redemption.