What does the reader learn about the characters of the narrator and the old man, in Ernest Hemingway "Old Man and the Bridge?"

The narrator seems to be with the army that is
anticipating the attack of the enemy from somewhere beyond the bridge.  The narrator may
be a scout of some kind.  He tells us that his job is to cross over the bridge, assess
how close the enemy is and return.  He notices the old man as he crosses the bridge to
do his job, and when he returns, although most of the peasant traffic has gone, he finds
the old man still there.  He strikes up a conversation with the elderly gentleman and
tries to encourage him to move on to a safer location.

The
reader learns that the old man has left San Carlos. It is his home town and he reports
that he was the last to leave, departing only because of the danger of artillery fire.
The elderly man reports that he has no politics, taking neither side in the war raging
around him.  He also says that he has no family. The old man reports that he was in San
Carlos caring for animals: two goats, a cat, and four pairs of pigeons. The old man was
told that he really had to leave because of enemy fire.

The
man is exhausted and having a hard time finding the energy to move on. He speaks to the
soldier (narrator) about the animals. He is worried about what will happen to them; if
it was dangerous for him, will it not also be dangerous for the
animals?

The soldier tries to comfort the man, and once
again encourages him to leave, but the old man becomes more mentally unfocused; and when
he rises, he sways and sits back down.

We get the sense
that when the soldier leaves, the old man is still seated next to the
bridge.