It's not that we owe the devil anything, it's that the devil has/had held us captive. The ransom is paid to free us from that unlawful and cruel captivity.
The devil thought this was a good deal, since he gets the very Son of God, but it is turned against him. His new prize is his defeat, destruction, and downfall.
-CryptoLutheran
What I see is that the Devil saw an opportunity, he was taking out yet another leader that opposed him. The Devil did what the Devil normally does, death is a weapon for him. The powers and principalities threw everything at him they had and couldn't hold him. That's not exactly why they lost, the angels in heaven when they fight against him overcome through the blood of the Lamb. Life wins over death, I think that is the whole idea here. Justice being satisfied, mercy can now move forward and rescue those who were in bondage, the Devil who is the ultimate opportunist, continues to pursue lies and murder.
But there was at least one life he could not end, bear in mind Jesus wasn't killed, he laid down his life. Perhaps the Devil can be seen as the jailer who thought he had an unbreakable bond, only to see the captives freed. I just don't like the term 'ransom', it's like a ransom paid for a hostage, it really doesn't work that way.
Therefore, since the children have flesh and blood, He too shared in their humanity, so that by His death He might destroy him who holds the power of death, that is, the devil, and free those who all their lives were held in slavery by their fear of death. For surely it is not the angels He helps, but the descendants of Abraham. (Hebrews 2:14-16)
I sometimes wonder about the crucifixion, how it broke the stranglehold the Devil had on the world. I've never been comfortable with Satan being allowed into the heavenly courts, always wondered why God doesn't just shut this nonsense down. Then you encounter the angels fighting against the dragon, and they overcome through the blood of the Lamb. For me, it's the power of an indestructible life that brings the demise of the Devil, sin and death.
I guess I have some issues with ransom theory, nothing all that meaningful. Atonement is a very big deal in Leviticus and very much emphasized in the New Testament witness. The price of sin is paid to God, and as the gospel teaches, by God.