en_tn_condensed/phm/01/10.md

my child Onesimus

"my spiritual son Onesimus"

Onesimus

The name "Onesimus" means "profitable" or "useful". He was apparently Philemon's slave and had stolen something and run away.

whom I have fathered in my chains

"who became my spiritual son when I taught him about Christ and he received new life while I was in my chains" or "who became like a son to me while I was in my chains"

in my chains

"while I was in prison"