Theophylact of Ohrid — on Phlm 1:2 (Commentary on Philemon)

“"And to Apphia, (our) beloved (sister), and to Archippus, our fellow soldier." Perhaps Apphia was the wife (of Philemon), and Archippus a friend. If he is a fellow soldier, then he will take part in this as well. This was the very same (Archippus) about whom he writes in the Epistle to the Colossians: "Say to Archippus, Take heed to the ministry which thou hast received" (Col. 4:17). "And your household church." The apostle calls "church" all the believers in the house (of Philemon), including even the slaves. Notice the humility — he appeals to them as well, so that they might assist him in his request.”