Son of Simon Iscariot. "Kerioth" was a town in Judea. This means Judas was likely the only non-Galilean among the Twelve. He was an outsider by geography—a southerner among northerners.
Jesus chose him. Jesus prayed all night before selecting the Twelve (Luke 6:12). Judas was not an accident; he was a chosen instrument, but his will remained free to reject the Master he followed.
He was formed by Hidden Greed. John 12:6 tells us he was a thief who stole from the money bag. He projected an image of care for the poor ("Why wasn't this perfume sold?") while harboring a heart of avarice.