Much in the way that films today have a “post-credit” scene, John adds an additional event to his story following the conclusion. Much like those film scenes, this story serves to give additional insights and to look ahead to the continuing story of the Gospel.
After the resurrection, but before the coming of the Holy Spirit, the disciples are coming to terms with life without Jesus leading and teaching them. Several of them naturally revert to what they know and head out fishing. After a fruitless night, they are headed into shore when Jesus calls to them from the shore. He tells them to try one more time and they hit pay dirt. They realize that it is the risen Lord.
As they eat together, Jesus offers another teaching moment. The last time they were eating together, Peter had claimed that he would stay true to Jesus even if it cost him his life. He had then denied Jesus three times. Jesus asks Peter about his love three times. Peter is humbled and grieved over his failing. He does love Jesus.
Jesus’ command for Peter is that he should care for the other followers of Jesus. Loving Christ entails doing what God has planned for us, the things that He expects from us. In Peter’s case this involves caring for and encouraging other believers to fulfill their calling. That is a responsibility a lot of Christians have in the Kingdom, and not just leaders. We have all be commissioned to make more disciples.
However, each follower has unique responsibilities in the Kingdom. When Peter is told that he will indeed die for his faith, he asks about John. Jesus reprimands Peter and says that his business is to stay true to his own calling. We are not to compare ourselves to others. Our calling is unique, our path with Jesus will be so as well. John’s calling and path will look very different than Peter’s. We don’t measure our faithfulness against anyone else’s.
At this moment, I imagine John looking at the camera and breaking the fourth wall. He lets us know that he has been the one telling the whole story. We can trust the veracity of his account because he was there the whole time. If he were to write down everything he saw and learned it would be too much for us to read. He has simply told us the stuff we need to know to follow Jesus ourselves.