Scum Villain Self-Saving System

After Shen Yuan dies in the real world, he wakes to find that he has transmigrated into the world of Proud Immortal Demon Way, a stallion (or harem) novel he hated (but nonetheless read all 1000+ chapters of). As he awakens, he's cheerfully welcomed by a System, who tells him his "account" is now bound to the character Shen Qingqiu, the original villain of the novel. He realises he has to change the story to avoid being tortured to death by the main character, Luo Binghe. But the System has other ideas, not allowing him to act too out-of-character to avoid derailing the plot.