You send the dragon a picture of your previous body that it murdered.

"So you want to be a Night Fury again hmm? Fine!" he rasped angrily, his rotting, boney tail lashing in agitation.

You fall into a dormant state as the wyrm leaves. An unknown amount of time later you come out of your dormancy as he returns with a struggling adult male Night Fury in his grasp, you can sense no wounds on this dragon and it was at the peak of its health. The wyrm chains the struggling dragon up onto the wall.

"Here is your new body, reach out and drain its lifeforce and bind yourself to its corpse," the wyrm instructed you.