Character foils are used to contrast characters and highlight particular properties of both. They are typically done most often with the protagonist. Foils can be rather extreme or very faint. Foils can also be used to compare things or places, but I will focus upon character foils.
Laertes and Ophelia serve as character foils to Hamlet in William Shakespeare’s Hamlet. Their reactions to the death of Polonius, their father, differs from Hamlet’s reaction to the death of his own father. Hamlet is based upon the convoluted and brooding Hamlet’s revenge plot against Claudius for killing his father. Hamlet is conflicted between his desire to take revenge and his fight against insanity. Laertes and Ophelia embody each of the issues independently.
Hamlet’s madness is rather enigmatic. While clearly stating his intentions “To put an antic disposition on”(I.v.191), his crazy behavior does occasionally appear to be honest. On the contrary, when Polonius dies, Ophelia’s grief-driven madness is rather different from Hamlet’s. Her true madness acts as a foil to Hamlet’s, and supports his claim of sanity. When Ophelia goes mad, she is described as “importunate, Indeed distract”(IV.iv.2-3). She is incomprehensible and appears to have lost her sense of purpose. Ophelia’s suicide also foils Hamlet’s. Though Hamlet laments “this too too solid flesh would melt, Thaw and resolve itself into dew, Or that the Everlasting had not fixed His canon ‘gainst self-slaughter”(I.ii.131-134), he never actually acts upon his broodings. Ophelia’s death however, is shrouded in mystery and very likely is a suicide.
On the other hand, Laertes is a foil to Hamlet’s revenge. Upon learning of his father’s murder, Laertes’ quickly takes action to get revenge for his father. He cries “let him come. It warms the very sickness in my heart That I shall live and tell him to his teeth, ‘Thus diest thou’”(IV. vii. 57-60). While similar to Hamlet’s thirst for revenge, Laertes acts immediately.