What does 2 Timothy 4:12 mean?

In this passage, Paul has been offering updates on his various ministry partners. Here, he mentions Tychicus, whom Paul has personally dispatched to Ephesus. Timothy personally knew Tychicus, from their travels with Paul (Acts 20:1–6). When Paul wrote to the Ephesian believers during his first imprisonment, it appears Tychicus delivered the letter (Ephesians 6:21). Along with Onesimus, he also delivered Paul's letter to the Colossians (Colossians 4:7).

Interestingly, Tychicus was also mentioned with Paul prior to his second Roman imprisonment. In Titus 3:12 we find, "When I send Artemas or Tychicus to you, do your best to come to me at Nicopolis, for I have decided to spend the winter there." They were in Nicopolis together sometime prior to Paul's arrest. After Paul's arrest, he was with him at least some time in Rome, then traveling to Ephesus. The purpose of his travel there is not explained.

The fact that Tychicus has been sent to Ephesus, where Timothy is, suggests that Paul intends him to serve as a substitute for Timothy so he can travel to see Paul. This is supported by Paul's very next comment to Timothy, in verse 13: "When you come."