Final answer:
The theme highlighted by the last lines of both acts is the transformation of good into bad and the shifting alliances between friends and foes.
Step-by-step explanation:
The question refers to the last lines of Act I and Act II in a play, asking what theme is underscored by both. The question is specifically about the themes of transformation and the blurring of binaries such as good and evil or friends and foes. From the given texts, one can understand that these lines reflect the theme that things are not inherently good or evil and that alliances can change, turning friends into foes and vice versa.