How does Jesus's Old Testament identity as Son of David and Son of God enable Him to fulfill the demands of the scroll in Revelation 5?
Jesus, depicted in the Old Testament as Son of David and Son of God, possesses the kinship needed to fulfill all the scroll's demands. Because He already accomplished the work of the cross, He comes before the Father and declares He will do it, paying off the mortgage.
Les explains that in the scene, God the Father is on the throne while God the Son is at the Father's right hand, not seated on the throne. When John is shaken that no one is able to open the scroll, God the Son comes before God the Father and says, "I'll do it. I'll pay off that mortgage." John assumes He can do it because He already accomplished the work of the cross. Jesus is also depicted throughout the Old Testament as the Son of David and the Son of God, so in kinship He can fulfill all those demands.