Demas the Traitor and Other Fellows (Philemon 1:19-25)

This study was done using the Amplified Bible, which I don't have permission to publish, so I will replace the verses here with the World English Bible (a modernized version of the ASV).  Because of that some of the comments may not totally make sense because the AMP has expanded explanations.  I would highly recommend going to a site like BibleGateway.com where you can read the AMP version for free.

19 I, Paul, write this with my own hand: I will repay it (not to mention to you that you owe to me even your own self besides). 

A.  Paul here takes yet again the same route at Jesus, taking the debt of another with nothing to gain but friendship with a former slave.  He is bartering for the freedom of his friend in a more practical way now, and in a more self sacrificial form.  Not just asking a favor, but offering to pay the price for it.

20 Yes, brother, let me have joy from you in the Lord. Refresh my heart in the Lord. 

A.  Paul begins to appeal to the man who owes him his very being for joy and refreshing.  He found these things in the work of the Gospel rather than worldly sources.  

21 Having confidence in your obedience, I write to you, knowing that you will do even beyond what I say.

A.  Paul is confident because of his knowledge of Philemon.  Knowing that it wouldn't be a guilt trip for him to ask such a favor, but that Philemon would most likely see it as an honor to bless the apostle who had sacrificed so much for the Gospel.  He goes beyond simple obedience to suggest that Philemon would do even more than what he asked.  What exactly he means by this remains a mystery.  

22 Also, prepare a guest room for me, for I hope that through your prayers I will be restored to you.

A.  Here we see the faith of Paul in action.  He was in prison as he wrote this, and even though he did not know the exact amount of time he would be confined there, he believed that because of the prayers of Philemon and others he would be released.  This releasing did not depend on the officials of those who held him in prison, but on the will of God and His response to the prayers of His people.  To prepare a place to stay with no guarantee of freedom was an act of prophetic faith, an example to believers everywhere on how to act in that same faith.

23 Epaphras, my fellow prisoner in Christ Jesus, greets you, 

A.  We know little about Epaphras aside from the mention of him in Colossians 4:12 in which Paul says he was a Colossians as well.  Aside from that we know that he was also imprisoned for the Gospel, possibly at the same time as Paul though we do not know for sure.

24 as do Mark, Aristarchus, Demas, and Luke, my fellow workers. 

A.  These men were all known by Philemon, as this was not written to a church body.  It is also possible that Paul's mention of them to Philemon was a suggestion that they agreed with Paul's request for the freedom of Onesimus.  
B. Aristarchus is most likely the same man recorded to be with Paul in Acts 19:29 and other places.
C.  The only other mention of Demas is in 2 Timothy 4:10, in which Paul says he abandoned because of his love for the world and went to Thessalonica.

D.  Luke is most likely the same Luke of the Gospel of Luke and Acts.  As he often traveled with Paul we can reason this to be the probable case.

25 The grace of our Lord Jesus Christ be with your spirit. Amen.

A.  According to Adam Clark, the word "your" in the verse is plural, meaning the blessing to go to all who were in the church at his house.