Mio padre?  
One character in this work sings a duet on the song "Ciel, mio padre!  Rivedrai le foreste imbalsamate", and had earlier sung "Che veggo!  Egli?  Mio padre?  Anch'io pugnai" after disguising himself and claiming to have been killed in battle.  That character is the father of another character who sings the arias "Ritorna vincitor" and "O patria mia" after watching the man she loves go to war against her own country of Ethiopia.  That character would later die in the arms of her lover in the vault of a temple of Vulcan after singing "Immenso Ftha", and a duet, "La fatal pietra sovra me si chiuse" with her lover Radames.  For 10 points—name this work about an Ethiopian princess living as a slave in Egypt, an opera by Giuseppe Verdi.
One character in this work sings a duet on the song "Ciel, mio padre!  
Aida