The Friar appears to be the only priest in a community entirely composed of Catholics. He is everyone's confessor, so he is involved in everyone's life.
Friar Lawrence wants Romeo to do different things depending on what part of the play you are talking about. When they first meet, the friar tells Romeo to go slowly in his relationship with Juliet (as if!).
Friar Laurence married off Romeo and Juliet.
Friar Laurence is the friar who marries Romeo and Juliet.
Friar Lawrence married Romeo and Juliet in his cell.
Juliet, Romeo, Tybalt, Nurse, Benvolio Or . . . Juliet, Romeo, Friar Lawrence, Nurse, Capulet Or . . . Juliet, Romeo, Friar Lawrence, Capulet, Tybalt Or . . . Juliet, Romeo, Capulet, Mercutio, Tybalt Or basically Romeo and Juliet and any three of Nurse, Friar, Capulet, Mercutio, or Tybalt.
Romeo, Juliet, and Friar Lawrence are in Friar Lawrence's cell.
The audience knows that Romeo has a close relationship with Friar Lawrence because Romeo confides in the friar about his love for Juliet, seeks his advice on important matters, and trusts him with their secret marriage. The friar also plays a key role in helping Romeo and Juliet be together, showing a deep bond between them.
He hopes that it will reconcile the feuding families. Which it does, eventually.
"Wisely and slow; they stumble that run fast."
Friar Lawrence was the priest in Romeo and Juliet
The friar.
Friar Lawence