Judas needed to identify Jesus because it was dark and because, even though many people knew about Jesus, far fewer had really seen Him up close. Judas turned the symbol of friendship, a kiss, into a symbol of hypocritical betrayal with his action. His greeting was to mark Jesus, not to show affection and honor Him. Judas kissed Jesus repeatedly, loudly, and effusively (Gr. katephilesen). [source][source][source]
Jesus" greeting, "Friend," was not intimate but gracious. Jesus" following words could have been either a statement or a question. If they were a statement, they reflect Jesus" sovereign control in this situation. If they were a question, they offer an ironic rebuke. Of course, Jesus knew why Judas had come. [source][source][source]