Symbols and Relationships

Per Sona:

In House made of dawn, there are many similarities between Francisco, Abel's grandfather, and
Ben shows a paralleism between Abel's life in L.A. and Walatowa. There are always dual characteristic in this novel like Ben and franciso, Milly and Angela, and Pries of sun and Father Olguin.
What does this dualism represent?

From Prof. Shaubb's lecture, he talked about Eagle as a symbol, and i think it represent freedom.
what other symbolic figures are in this novel other than eagle?
why do you think Momaday choose that specific figures?