Both Timothy and Titus worked ceaselessly in the new Christian churches of the Eastern Mediterranean. Paul passionately believed that the gospel was open to all - both Timothy and Titus, as Gentiles, were used in different ways by Paul to demonstrate the need to spread the new faith to Jew and Gentile alike.
We do not know what happened to Titus, but there is a 4th century tradition that Timothy was beaten to death by a mob in Ephesus when he tried to put a stop to a festival for the pagan God Dionysius. Both Timothy and Titus accompanied Paul on at least one of his missionary journeys and they were clearly valued members of Paul's staff.
