How would you had handle Darkstalker?

What could have been a better way to handle Darkstalker? Something to point out first Darkstalker was aware that the strawberry was going to change him. He knew it was going to change him. The only reason he thought it didn't it because it did not cross his mind that they enchanted it with his scroll. When he ate it it was with the intention to mock them. Like "Ha, ha, I will eat this strawberry but won't affect me because I protected myself form other animus magic".

But moving all to the real question. What you would have handle the Darkstalker conflict? I know some wished he had decided to change by choice. But re-reading the series Darkstalker wasn't the type of dragon who would do that. He always thought he was always right. All his decisions were the best for everyone. He will never felt guilty what he did to everyone or say "Oh no I am really a bad dragon. How could have make a lots of mistakes". I am sorry but Darkstalker was never going to voluntary change. He was still trying to find a way to take over Pyrrhia even with the earrings. He had no regrets sending the plague to the Icewings and possibility make Winter an endling.

Anyway do you think it would have been better for Darkstalker to change voluntary? To kill him? Or do something different like shrink him to an average size and erase all his memories.