The first thing to note about the guest is the obvious trait that he is ambitious. When he arrives at the house, he is weary but is immediately brightened by the warm response he gets from the family. The guest is described with a series of balanced characteristics: proud and gentle, haughty but a brother to the poor, and a man with dreams marked by loftiness and caution.
The guest was also a loner, a solitary man with great ambition.
The secret of the young man's character was a high and abstracted ambition. He could have borne to live an undistinguished life, but not to be forgotten in the grave. Yearning desire had been transformed to hope; and hope, long cherished, had become like certainty, that, obscurely as he journeyed now, a glory was to beam on all his pathway, -- though not, perhaps, while he was treading it.
Up to this point, the ambitious guest has done nothing noteworthy but he is determined that he will not die until he has done something incredible, and this will establish his legacy. The guest's ambitious ruminations affect the usually contented family and they begin to speculate about more extravagant things in their own lives. The guest dreams of doing great things but also seems to insist on warranting a monument for himself. So, he has wandered alone while dreaming of greatness, which is admirable but it is also dubious because part of his motivation is the self-glorification of a monument and/or being remembered for greatness.