Then James and John, the sons of Zebedee, came to him. “Teacher,” they said, “we want you to do for us whatever we ask.””What do you want me to do for you?” he replied.
They replied, “Let one of us sit at your right and the other at your left in your glory.”
“You don’t know what you are asking,” Jesus said. “Can you drink the cup I drink or be baptized with the baptism I am baptized with?”
“We can,” they answered.
Jesus said to them, “You will drink the cup I drink and be baptized with the baptism I am baptized with, but to sit at my right or left is not for me to grant. These places belong to those for whom they have been prepared.”
When the ten heard about this, they became indignant with James and John. Jesus called them together and said, “You know that those who are regarded as rulers of the Gentiles lord it over them, and their high officials exercise authority over them. Not so with you. Instead, whoever wants to become great among you must be your servant, and whoever wants to be first must be slave of all. For even the Son of Man did not come to be served, but to serve, and to give his life as a ransom for many.” (Mark 10:35-45)
James and John were among the closest of Jesus’s disciples. Because of this, they felt they should be rewarded by being next to Jesus when he came into his kingdom–one at his right and the other at his left. In the Matthew account of this story (Matthew 20:20-28), their mother gets into the act. Of course the other disciples wanted no part of this.
James and John were only doing what any sensible, self-respecting political aide would do: ask the candidate for a prominent position on the cabinet after the election is won. “Don’t forget who helped you win this thing.” Their actions, and the virulent response of the other disciples to them, would make perfect sense if Jesus were a political/military messiah and his kingdom were a political/military affair.
Indeed, much of Jewish culture and tradition had the same expectation of the coming Messiah. That is why the Pharisees felt so threatened by Jesus–they did not want him taking away their power.
But they didn’t get it. Nobody got it. Not the Pharisees, not the rank-and-file first century Jews (a majority of them, at any rate), not the disciples, and certainly not James and John. They had no idea what Jesus was really up to or what his kingdom would really be all about. If they did, they certainly didn’t want to believe it, because if it was true then their most cherished expectations of what the coming kingdom was to look like would have to go.
So Jesus made things clear for James and John. He asked if they could drink the cup that he would drink and be baptized with the baptism that he would undergo. They answered yes, no doubt hoping that if they went along with this then Jesus would give them what they asked for. I doubt seriously that they fully knew (in that moment, at least) what they were saying yes to. Jesus responded by saying that it was not for him to choose who would get to be at his right and left when he came into his kingdom, that those places were reserved for those for whom they were prepared.
We know the end of this story. James and John did in fact drink of the same cup that Jesus drank of, and undergo the same baptism that he underwent. But Jesus’s coming into his kingdom proved to be a far different sort of affair than anyone who had expectations of a political/military messiah was expecting.
James and John did not get the places on Jesus’s right and left. Those places went to two common criminals. One died cursing Jesus to the very end. The other heard Jesus say, “Today you will be with me in Paradise.”