After the Villainous Master Failed His Mission

The protagonist is bound to a villainous master System and must complete tasks to bully, exploit, and suppress the male lead, then die by his sword to help him ascend to immortality.

The protagonist diligently completes his tasks, but the male lead just won't kill him.

Male lead: My master must have a reason for doing this!

The protagonist, furious: You ungrateful brat, ahhh!

Then the mission fails, and the protagonist fakes his death and returns to the transmigration bureau, only to be told by the System: This is bad! Your disciple has gone dark. You have to go back and win him over!

The protagonist: ?

When the protagonist returns, a hundred years have passed. The male lead hasn't just turned evil, he's become the great demon lord feared throughout the cultivation world.

The protagonist has just returned to his old master's body, only to find himself lying on an ornate bed, a delicate anklet fastened around his ankle, with a long chain attached to the foot of the bed.

His disciple, now a demon lord, is holding him tightly and calling him master in a lovesick voice, his eyes filled with dark possessiveness.

The protagonist: .

What did you do to me during the hundred years I was gone?

A puppy-like male lead who works tirelessly, firmly believes his master cares for him, and immediately goes dark and berserk when his master dies, turning from a sweet puppy into a rabid dog x a peerlessly beautiful, wonderful master who actually just wants to laze around.

Theme: If you have a teacher's virtue, you'll get ( )