I Only Envy Mortals but Not Immortals

The divine dragon has its head but not its tail, and the immortal is famous but not his shadow. There are legends of immortals everywhere in this world, but no one has ever seen them with their own eyes. From the moment Lu Yu came here, he formed an indissoluble bond with the immortal. He used his mortal body to inherit his natural talents, did rogue things in the name of the immortal, and performed righteous deeds in the name of the rogue. One step back is an immortal, one step forward is a mortal, one looks like an immortal but not an immortal, one looks like a human but not a human being, right and wrong are not grudges, strength determines the world.