Mark 14:45 After coming, Judas immediately went to Him, saying, “Rabbi!” and kissed Him.

Who comes and immediately goes up to Jesus?

Judas (14:45)

How does Judas address Jesus?

“Rabbi!”

[“Title of respect, meaning ‘my great one,’ or ‘my superior one,’ used in Jesus’ day for Jewish religious teachers. According to Matthew 23:7, ‘rabbi’ was evidently used as a common title of address for the Jewish scribes and Pharisees; however, in the NT it is most commonly used as a title of respectful address when others were speaking to Jesus. It was used by Nathanael (Jn 1:49), by Peter and Andrew (Jn 1:38), by Nicodemus (Jn 3:2), by the disciples as a group (Jn 9:2; 11:8), and by a crowd generally (Jn 6:25). Mary Magdalene (Mk 10:51) and blind Bartimaeus (Jn 20:16) both use the longer form, ‘rabboni,’ to address Jesus directly, thus indicating even more profound respect than the use of the mere title, ‘rabbi.’ By the time of the writing of John’s Gospel, the title ‘rabbi’ meant ‘teacher’; and this John says explicitly in 1:38 and implicitly in 3:2).

         Jesus condemns the scribes and the Pharisees for their evident pride displayed in their love of being greeted in the marketplaces and their insistence on having men call them ‘rabbi’ (Mt 23:7, 8). Jesus prohibited the use of the title for his own disciples, saying, ‘You are not to be called Rabbi.’ However, Jesus’ prohibition was more against seeking to be called this and insisting on it than the mere legitimate possession of the title itself. In fact, several people did use the title of Jesus in a reverent way and they were not in any way rebuked” (Baker Encyclopedia of the Bible, V 2, p. 1815).]

What does Jesus say concerning being called Rabbi in Matthew 23:1-12

Matt. 23:1    Then Jesus spoke to the crowds and to His disciples,  2 saying: “The scribes and the Pharisees have seated themselves in the chair of Moses; 3 therefore all that they tell you, do and observe, but do not do according to their deeds; for they say things and do not do them. 4 “ They tie up heavy burdens and lay them on men’s shoulders, but they themselves are unwilling to move them with so much as a finger. 5 “But they do all their deeds to be noticed by men; for they  broaden their  phylacteries and lengthen  the tassels of their garments. 6 “They love the place of honor at banquets and the chief seats in the synagogues, 7 and respectful greetings in the market places, and being called Rabbi by men. 8 “But do not be called Rabbi; for One is your Teacher, and you are all brothers. 9 “Do not call anyone on earth your father; for  One is your Father, He who is in heaven. 10 “Do not be called leaders; for One is your Leader, that is, Christ. 11 “ But the greatest among you shall be your servant. 12 “ Whoever exalts himself shall be humbled; and whoever humbles himself shall be exalted.

What had Judas given as a signal to the crowd with swords and clubs?

“Now he who was betraying Him had given them a signal, saying, ‘Whomever I kiss, He is the one; seize Him and lead Him away under guard’” (14:44).

What does Judas do after coming up to Jesus and saying, “Rabbi!”?

“he kissed Him” (14:45).

Father,
You reign from on high in Your holy temple, exalted and enthroned in majesty and glory above the earth. You observe outward actions while discerning perfectly the inward motives of the heart. You are the God Who knows. Nothing can be hidden from Your penetrating gaze. No one can escape the scope of Your sovereign jurisdiction. Glory to You, Mighty King, and glory to Jesus, Son of God, Savior, King, Lord over all. 
In Jesus’ Name I pray, Amen.