Friar Laurence is presented as a holy man who is trusted and respected by the other characters. The Friar's role as the friend and advisor to Romeo and Juliet highlights the conflict between parents and their children within the play. The centrality of the Friar's role suggests a notable failure of parental love. Romeo and Juliet can't tell their parents of their love because of the quarrel between the two families.
In their isolation, Romeo and Juliet turn to the Friar who can offer neutral advice. At first, the Friar can't believe how quickly Romeo has abandoned Rosaline and fallen in love with Juliet, so he reminds Romeo of the suddenness of his decisions. The Friar uses the formal language of rhyme and proverbs to stress the need for caution to Romeo. However, he agrees to marry Romeo and Juliet in the hope that their marriage will heal the rift between the Montagues and the Capulets. His decision to marry the lovers is well-meaning but indicates that he has been naive in his assessment of the feud and hasn't reflected on the implications of Romeo and Juliet's clandestine marriage.
The conflict between youth and old age also manifests itself in the Friar's relationship with Romeo and Juliet. When Friar Laurence tries to soothe Romeo's grief at the news of his banishment with rational argument, Romeo quickly responds that if the Friar were young and in love, he wouldn't accept such advice any better.
The Friar's knowledge of plants — especially their dual qualities to heal and hurt — play an important role in the action that follows. His attempts to heal the feud by reversing nature — causing Juliet's "death" in order to bring about acceptance of her life with Romeo is notably unnatural. The Friar must extricate Juliet from the tomb in order to save her life — another reversal of nature. This use of nature for unnatural purposes precipitates many of the consequences leading to the tragic conclusion of the play. Ultimately, the Friar acts distinctly human — he flees the tomb and abandons Juliet.