Answer:
Brutus is motivated by his nobility, Cassius is motivated by his greed.
Step-by-step explanation:
A character foil is one that stands contrasting with other character, which is most of the time the protagonist. The character foil will show opposite personality traits, values and actions working sometimes as an antagonist to the protagonist. Like the protagonist can be the hero and the antagonist can be a villain. In this sets Brutus and Cassius show opposite motivation.