Sunshine for the Shattered Prince

I only meant to drop off my caravan's cargo in the capital and leave. But then I saw him. Prince Drazhan, starved, bleeding, and forced to eat scraps in the snow while the court mocked the jagged obsidian scales creeping up his neck. Knowing this abused boy was destined to become the monstrous Calamity who would freeze the continent, I did what any terrified transmigrator would do: I threw my brightest quilt over him and loudly proclaimed his scales were more breathtaking than cut diamonds. My plan was simple. I would act like a clueless, cheerful fool, shower him with aggressive affection, praise his terrifying traits, and slip away once his trauma was healed. As years pass in a melancholic blur of winter storms, he has transformed from a broken child into a terrifyingly quiet young man. But I’ve made a fatal miscalculation. I thought his villainous awakening was triggered by a hatred for humanity. Instead, the prophecy dictated he would destroy the world to protect his one obsession. Drazhan isn't healing; he's secretly building an inescapable fortress in the mountains. If my planned departure is the very catalyst that dooms the realm, how do I escape a beast who has locked the cage from the inside?