What was the relationship between Judah and Benjamin?
Judah took responsibility for his youngest brother, Benjamin. In Egypt he offered to stay as a slave in his place. Genesis 43:8-9; Genesis 44:33
What the Bible says
Genesis 44:32
Let me be thy proper servant, who took him into my trust, and promised, saying: If I bring him not again, I will be guilty of sin against my father for ever.
Genesis 44:33
Therefore I thy servant will stay instead of the boy in the service of my lord, and let the boy go up with his brethren.
Douay-Rheims Bible (Challoner revision), public domain.