Who is argus and why can't he never be surprised?

Argus ( in the Percy Jackson Series) was Hera's servant and was a  guard to her cow. He can't be surprised because he is literally covered with eyes ( you can't sneak up on him) which is why he was a good guard

Atahualpaemperor of the inca empire who rose to the throne after winning a civil war between him and his brother.  -he refused to become a spanish vassal or christian.-francisco pizarro kidnapped him and demanded a huge ransom.  -pizarro's secretary described him as "a man of thirty years, good-looking and poised, somewhat stout, with a wide, handsome, and ferocious face, and the eyes flaming with blood."-after the ransom was paid, atahualpa was killed by pizarro