After James and John requested to sit on the right and left of Jesus when he rules, Jesus told them what will happen and how they should act.

Mark 10:35-45

35 Along the way, James and John, who were the two sons of Zebedee, approached Jesus and they said to him, “Teacher, please do for us what we will ask you to do!” 36 He said to them, “What do you want me to do for you?” 37 They said to him, “When you rule gloriously, let us rule with you. Let one of us sit at your right side and one sit at your left side.” 38 But Jesus said to them, “You do not understand what you are asking for.” Then he asked them, “Can you endure suffering [MTY] like I am about to suffer? Can you endure being killed [MTY] as I will be killed {people killing you as they will kill me}?” 39 They said to him, “Yes, we are able to do that!” Then Jesus said to them, “It is true that you will endure suffering [MTY] like I will suffer, and you will endure being killed as I will be killed {people killing you as they will kill me}. 40 But I am not the one who chooses the ones who will sit next to me and rule with me. God will give those places to the ones he appoints.”

41 The other ten disciples later heard about what James and John had requested. As a result, they were angry with them because they also wanted to rule with Jesus in the highest positions. 42 Then, after Jesus called them all together, he said to them, “You know that those who rule the non-Jews enjoy showing that they are powerful. You also know that officials enjoy commanding others. 43 But do not be like them! On the contrary, all those among you who want God to consider them great must become like servants to the rest of you. 44 Furthermore, if anyone among you wants God to consider him to be the most important, he must act like a servant for the rest of you. 45 You should imitate me. Even though I am the one who has come from heaven, I did not come to be served {for others to serve me}. On the contrary, I came in order to serve others and to allow others to kill me, in order that my dying for people would be like a payment to rescue many people from being punished {God punishing them} for their sins.”