Author: Though the greeting includes both Paul and Timothy, with the use of "I" throughout the letter we see that Paul is the primary author.
Audience: This letter is an appeal to Philemon to receive Onesimus back as a beloved brother and not just a bondservant.
Location: Most likely Paul's Roman imprisonment (Acts 27-28). Philemon lived in the city of Colossae.
Time: Probably A.D. 62, about the same time as Philippians, Colossians, and Ephesians.
Purpose: Philemon was a wealthy Christian living in Colossae. Onesimus, one of Philemon's bondservants fled to Rome, possibly stealing money or property of Philemon. Onesimus came into contact with Paul and became a Christian at some point and spent time helping Paul in his imprisonment. Paul wants to make things right and send Onesiumus back to Philemon and wrote this letter to appeal to Philemon to receieve Onesimus back as a beloved brother and not just a bondservant.