Jesus' thirst on the cross was a product of His humanity and His deep spiritual thirst for the Living Water He was making available to us.
Jesus is done. He's done everything He came to do. He hasn't declared it yet, but, in fact, his work on the cross is an accomplished fact and he is ready to die. However, there is one last thing He wants to round out, one last detail.
He is filling up the Scriptures. This is not an explicit