I Am the Protagonist's Tool

Lu Ling traveled to this world with only one purpose: Train the protagonist to defeat the final boss. Then the protagonist reaches the peak of his life. Relatives and friends gather together and happily end with flowers. Originally, this task was not difficult at all, because the protagonist has the halo of being the protagonist and can achieve a perfect ending no matter what the situation. He, the male supporting actor and the promoter of the story, only serves as the icing on the cake. As a result, the will of the universe told me that the luminous ring was sent by mistake. Is the halo of the protagonist sent to this product a defective product? The protagonist's aura cannot be changed once it is released. In order to make up for it, you can upgrade yourself from an ordinary male supporting actor to an important male supporting actor, and rely on your improved ability to protect him until the end? ??? Damn, I became the protagonist's nanny? ! This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.