How does the apostle Paul's appeal to Philemon regarding Onesimus challenge or subvert the social norms and legal practices concerning slavery in the Roman Empire?

A Paul explicitly condemns the institution of slavery and demands Philemon's immediate obedience to manumit Onesimus. B Paul strategically uses the language of kinship and brotherhood in Christ to appeal to Philemon's conscience, gently urging him to receive Onesimus as a beloved brother rather than a mere slave, thus challenging the dehumanizing aspects of slavery without directly attacking its legality. C Paul emphasizes Philemon's legal right to punish Onesimus as a runaway slave, but encourages him to show mercy to avoid legal repercussions from the Roman authorities. D Paul offers to financially compensate Philemon for the loss of Onesimus's labor, essentially buying Onesimus's freedom through a financial transaction, thus reinforcing the economic aspects of slavery.