What was the relationship between Stephen and Peter?
The Twelve, with Peter among them, asked that seven men be chosen. Stephen was one of them, and the apostles prayed and laid hands on them. Acts 1:13; Acts 6:2-6
What the Bible says
Acts 6:3
Wherefore, brethren, look ye out among you seven men of good reputation, full of the Holy Ghost and wisdom, whom we may appoint over this business.
Acts 6:6
These they set before the apostles; and they praying, imposed hands upon them.
Douay-Rheims Bible (Challoner revision), public domain.