Who is Epaphroditus? (25): This man is from Philippi, and the church there sends him to deliver a gift to Paul. They also commission him to "minister to [his] need." Thus, he faithfully travels to Rome, even "risking his life" to fulfill this service to the imprisoned apostle. But there's more. As a partner in ministry to Paul, he is called "my… fellow worker and fellow soldier."
Epaphroditus' care (26-27a): There is yet another side to this man. He cared deeply for the church. Paul explains that Epaphroditus’ care for them is the reason why Paul is sending him back: "I thought it necessary to send [him] to you… because he was longing for you all and was distressed because you had heard that he was sick" (2:25-26). There is a lot of caring going on here. The church is grieved over this man's illness. This man, in turn, is distressed over their grief for him. This was especially hard for Epaphroditus, since he was no longer ill. "God had mercy on him." The church was grieving for nothing! To put an end to all this grief and distress, Paul decides to send this man back.
Paul's care (27b-28): As he explains this decision, Paul reveals his own care for both the man and his church. He does this by speaking of "sorrow upon sorrow." The first sorrow is over Epaphroditus' illness and possible death, but God spares Paul by healing this man. The second sorrow is over the church's grief over their man's illness. Like Epaphroditus, Paul too is distressed over their sadness. So, when God heals this man, the decision is a no brainer. Paul wants comfort for both parties ASAP. So, he prioritizes restoring joy to both parties rather than retaining Epaphroditus as a partner in ministry. What a wonderful joy all would have when the healthy man shows up at their door!
Receive and honor (29-30): Since the church expects him to remain there to serve Paul, he can see the potential for an accusation that Epaphroditus failed his mission. To mitigate this, he tells them to receive him "with all joy." More than that, the church is to honor Epaphroditus (and others like him) for their willingness to lay down their lives to serve others, just as the Lord taught us.
 This is Epaphroditus of Philippi, distinct from "Epaphras" of Colossae. The former is a minister of the gospel from Philippi. The latter founded the Colossian church (Col. 1:7, "you learned it [the gospel] from Epaphras") and he faithfully ministered to the churches in Asia. Cf. Col. 4:13 ("he has a deep concern for you and for those who are in Laodicea and Hierapolis"). All three cities are in modern day Turkey, which is ancient Asia.
 Paul already "sent him" (2:28) at the time of this letter. Epaphroditus probably delivered the letter himself.
 Cf. 4:18, " I have received everything in full … having received from Epaphroditus what you have sent."
 The church intended for Epaphroditus to deliver the gift and to remain at Rome to minister to Paul personally. They did not expect him to return so quickly. But due to Paul's care for the church and for this man, he sends him back. To eliminate any accusation that Epaphroditus violated his mission, Paul takes full responsibility for his return (2:25, "I thought it necessary to send to you Epaphroditus"). Paul also makes sure that he will be warmly received. He tells the church to "receive him then in the Lord with all joy" (2:29).
 This was "risking his life to complete what was deficient in their service to him" (2:30).
 The pronoun "my" (in the first phrase "my brother") applies to all three titles so that this man is seen as "my fellow worker" and "my fellow soldier." The position of the Greek article indicates this.
 This man is just like Timothy, a "fellow worker" (Rom. 16:21), and Archippus, a "fellow soldier" (Phm. 1:2).
 "Mercy" (or "pity") as physical healing is within the term's range of meaning. At one level, God's mercy forgives sinners. At another level, God's mercy provides for the poor. At yet another level, God's mercy heals the sick. E.g., "have mercy on me!" is a cry for healing by the ten lepers and a blind man (Luke 17:13; 18:38).
 Concern for the church's grief is the second "sorrow [lu-pē (λύπη)]." This is explained in 2:28, where "less concerned about you" is literally "unsorrowful [a-lu-pos (ἄλυπος)] about you," or "less sorrowful" (NKJV).
 The sensitivity between all three parties is quite evident. However, sometimes believers can become callous toward others' illness and grief. After all, death is gain, right? And God is sovereign, right? This type of coldheartedness is foreign to Scripture. Recovery is sought after and desire for wellness is not condemned (cf. James 5:15 and 3 John 2). Even in death, we are to comfort one another (1 Thess. 4:18).
 Epaphroditus' distress would end when he knows the church has stopped grieving his illness. His return would bring relief to both immediately, though the trip to Philippi would still take ~40 days (O'Brien, 25).
 Jesus said: "love one another, just as I have loved you… that one lay down his life for his friends." (John 15:12-13). Cf. also 1 John 3:16 ("we ought to lay down our lives for the brethren").