Romeo is a complete romantic. First with Rosalind, and then with Juliet, Romeo feels that love is special, unique and true, and he lets himself be overwhelmed with the feeling of love when it occurs. He also thinks that it is worth risking everything for it, and sees this as a heroic enterprise.
Mercutio's views are very different. Mercutio instead mocks love and blind, intense romantic sentiments. He is witty and loves to make jokes, and in these, he constantly highlights the self-indulgence that goes on in the play.
Mercutio acts as a foil to Romeo by expressing the antithesis of the romantic feelings Romeo displays. Mercutio serves as a contrast to Romeo.
The fact that Mercutio serves as a foil to Romeo has significant implications within the play. This contrast allows us to appreciate how unreasonable and reckless Romeo can be in the face of love. It also emphasizes the consequences of having unchecked, strong feelings and acting upon them. More importantly, Mercutio reminds everyone of the power of fate and the dangers of dismissing it.
