Since I had a lot of time to mull over parshah Vayigash this Shabbos (see Ah, Welcome Home), I had a thought that I considered rather "Duh", which I wanted to share regardless.
Rabbeinu Tam notes that upon dispatching his brothers home to fetch their father and respective families, Yosef presented two sets of clothing to all the brothers except Binyamin, to whom Yosef gave five sets. Given the fact that sibling rivalry was precisely the ulterior reason for the sin committed by the brothers against Yosef, commentators consider this blatant favouritism problematic. Reasons to explain the extra lavishing upon Binyamin range from the material (Aitz Yosaif / Iyun Yaacov Megilla, who state that the 5 sets were equivalent in value to the 2 sets afforded the other brothers) to the psychological (Maharasha, who states that the other brothers understood the special connection Yosef had with Binyamin since they were sons of the same mother).
I would like to pose a different explanation. Midrash describes in extended detail the efforts that Yehuda took to persuade Yosef to return Binyamin to his father, while the other brothers silently watched. The purpose of their silence is that once again, as with the sale of Yosef, the position of the brothers was aligned with that of their natural leader, Yehuda. However, unlike with the sale of Yosef, Yehuda undertook his tactics of persuasion because it was his chance to do teshuvah for having instigated the sale. In turn, the other brothers where complicit in Yehuda's teshuvah; since silence is taken as a sign of agreement, that they remained silent during Yehuda's displays of physical strength and emotional oration belies their allegiance with him in his efforts.
Moreover, the reason that Yosef subjected his brothers to trials and suffering in his dealings with them in Mitzraim was to a) ascertain whether they had purged themselves of the sibling rivalry that had caused his sale, i.e., to determine whether they were loyal to Binyamin, and b) help them do teshuvah in this world to avoid suffering in Olam Haba. Therefore, once his brothers had unequivocally done teshuvah and displayed nothing but filial devotion to his younger brother, Yosef was no longer afraid to show special affection to his only full brother, and the baby of the group.
In other words, since they had done teshuvah and effectively rid themselves of the defect of filial jealousy, Yosef correctly assumed that being lavish with their baby brother was not dangerous.
If you disagree, as usual, feel free to comment/disagree. Gut Voch!