Paul walks a tight wire but he retains his integrity. Coercion does not validate, but violates the gospel. I no longer call you servants, because a servant does not know his master's business. Instead, I have called you friends, for everything that I learned from my Father I have made known to you. Then the Father will give you whatever you ask in my name.
Love can only work in the context of freedom.
Paul is willing to trust in the love of Christ to lead Philemon to do the right thing. Only Philemon could determine what love required of him in relation to Onesimus. To solve problems we must remind ourselves of what the love of Christ and other Christians has afforded us. So if you consider me a partner, welcome him as you would welcome me. If he has done you any wrong or owes you anything, charge it to me.