Usage patterns
〈人〉の子分になるto become someone's henchman/follower
When he was young, he became that boss's henchman.
〈人〉を子分にするto take someone on as one's follower/henchman
The boss took the skilled young man on as his follower.
子分を従えるto have followers under one's command
That man commanded many henchmen.