Tybalt, the kinsman to old Capulet, Hath sent a letter to his father's house. (II.IV.6-7)
A challenge, on my life. (II.IV.8)
City of Verona,Benvolio and Mercutio
Romeo will answer it. (II.IV.9)
Any man that can write may answer a letter (II.IV.10)
Benvolio and Mercutio are talking about how Tybalt sent a letter to Romeo asking for a duel/fight. (Revenge)
Alas, poor Romeo! He is already dead, stabbed with a white wench’s black eye, shot through the ear with a love song, the very pin of his heart cleft with the blind bow-boy’s butt shaft. And is he a man to encounter Tybalt? (II.IV.14-19)
Nay, he will answer the letter's master, how he dares, being dared (II>IV.11-12
The idea of revenge in this story is presented by the fact two families are in a chronic feud that continues out for an extremely long time. These families constantly decide to fight even in their younger generations rather than coming to a proper understanding.
This scene connects with the motif of revenge because the Capulets and the Montagues still are constantly trying to find ways to seek their revenge. In this scene Tybalt is trying to start a fight with Romeo (who are in the opposite families) in seek of revenge.
Shakespeare is trying to convey the motif of revenge through the conversation of Benvolio and Mercutio when their discussing the situation Romeo has gotten himself into with his family's enemy.