I Raised My Doomed Emperor

Seraphina, a modern office grunt, accidentally transmigrates into a novel as the villainous witch who is destined to die horribly. To rewrite her ending, she hides away in the forest, but ends up saving and taking in the original male protagonist, Damian, the future emperor. She gently raises him, teaches him magic, and the two gradually form a deep bond, embarking on an entirely new destiny.