In Canto 3, Charon gives two reasons why the Pilgrim shouldn't get into his boat. First, the Pilgrim is alive, and Charon shows that he perceives this when he calls him "the living man" in line 88.
More importantly, Charon, who, like many of the damned, has some knowledge of the future, gives the first of several references to the Pilgrim's eventual salvation. The "other road" and "lighter skiff" that Charon refers to is the angelic boat that carries souls to Purgatory (see Purgatorio, Canto 2). In other words, Charon is saying that when he dies, Dante will not go to Hell, but to Purgatory (and then eventually Heaven). Virgil then gives this same idea when, in lines 127-129, he explains why "Charon grumbles at the sight of you."