I believe the playwright was trying to convey that doubts about the relationship between the Conquistadors and Aztec natives through Cydaria and Cortez. The love Cydaria and Cortez is used to move the audience, as their love is forbidden and they must choose between their duty to their kings and passion of love. By the end of the play Cortez has won over Cydaria and it seems to me that Cydaria is a silent partner in the success of the Conquistadors, even though Cydaria had influence over Cortez. Cydaria has met her match in the foreign stranger, because both throw their duties to the side for individual desires and passions. Which is evident when Cydaria influences Cortez to try and stop the attack and stop the men from killing her father. Loyalty and their duties to their kingdoms are temporary things for both Cortez and Cydaria when they put love ahead of their political obligations. Instead of taking political action they relied on their love to ensure that everything would come out fine for both kingdoms, which was not the case. Cortez came out on top because he succeeded in accomplishing his mission while Cydaria was left with a kingdom in ruins, her father dead, and a man that was capable of loving more than one women at a time. The relationship is a metaphor for foreign policy and making it legible about what is right and wrong when dealing with foreign countries. It also suggests that an ethical approach when dealing with foreign countries would be best as exemplified through the torture of Montezuma and his high priestess.
The play serves to dramatize the cruelties of the Conquistadors and also the cruelties of other imperialist countries. The characters also represent the English politics and the current situation of the king. There is a fight for power between two kingdoms that challenge monarchy. Both Montezuma and Cortez are honorable leaders who both are influenced by love.