Yosef was the recipient of Yaakov’s special favor because of his unique attributes. As Rabeinu Bachya states, Yosef’s personality combined the outstanding qualities of all the other brothers. Yaakov perceived in Yosef a continuation of himself. Their facial features strongly resembled one another’s, and their life histories were strikingly similar. Pirkei D’Rav Eliezer states that Yaakov loved Yosef because he prophetically foresaw that Yosef was destined for eminence.
Above all, Yaakov loved Yosef for his Torah knowledge. Rashi cites Onkelos who defines ohbez ic as ohfj rc- the wise son. This is consistent with the Midrash which states that Yaakov imparted to Yosef the Torah knowledge he had gained from the Yeshivah of Shem and Ever. Yaakov provided a Torah education for each of his sons, exerting great effort to raise them as tzaddikim. To Yosef, however, he revealed secrets of the Torah which he shared with no one else. Nonetheless, it seems peculiar that Yaakov would teach Yosef “more” Torah than he had imparted to the other brothers.
We may suggest the following thought. The father and son relationship can be established in many ways. The two can go on outings together or work cooperatively on various projects. Another method to concretize this relationship is through Torah study. When a father and son establish a “chavrusa”, learning partner, relationship, this alliance is bonded for eternity. This partnership is not an emphemeral or vacuous experience, which continues on only as long as each member derives benefit from it. Rather, it is a holy relationship in which both individuals are fused into one being. Yosef was Yaakov’s “ben zekunim.” Their association was nurtured by Torah study. While Yaakov supervised the Torah study for all of his sons, Yosef was his “chavrusa”!