Saturn aspects in synastry are notoriously difficult to handle. Saturn represents depression, restriction, fear of rejection, distancing, as well as commitment. Saturn aspects are certainly binding, but come with many problems. Here are some descriptions of how hard aspects (i.e. the conjunction, square and opposition) from one person's Saturn to another's Sun, Moon, Mercury, Venus and Mars manifest in synastry.
Saturn Conjunct Ascendant
This Saturn person will influence the Ascendant person to be more mature, serious and businesslike in self expression and basic approach to life and to be more cautious. The Ascendant person can help the Saturn person to overcome fears. If Saturn is badly aspected in the comparison there maybe a threat to freedom of self expression and the Saturn person may regard the Ascendant person as immature, self-centered and impulsive