What Happens in Acts of the Apostles?

Mark, who's cousin to Barnabas feels like Paul's usurping the leadership and I think Mark gets a little upset. He goes back to Jerusalem. Now we find out later on that Paul and Mark get reconciled. And part of the good news is even good devout Christians can fight and not get along and yet they can be reconciled. So there's a reconciliation that happens over time with Mark and Paul.