Misidentifying the Villainous Immortal as the Savior

'''[Main story completed, sweet extras are being continuously updated~] I transmigrated into a dog-blood novel. My mission was to save the protagonist shou. I found the pitiful young protagonist shou and told him I wanted to take care of him. The little brat glared at me fiercely: "What are your intentions?" I spouted nonsense with a straight face: "Actually, you saved my life in my past life. I'm here to repay your kindness in this life." He actually believed me. How gullible. After much difficulty, I finally raised the little brat, but the system told me I had the wrong person. I mistook Gu Xuecheng, the great villain and City Lord of Lingxiao, for the protagonist shou. The only way t...