I'm the Inner Demon, So Why Does the Protagonist Want to Slay Me?

Su Lin transmigrated to the Myriad Worlds, bound himself to the “Heart Demon Comparison” System, and became the “heart demon” on the paths to growth of the children of destiny in the various worlds. The stronger the protagonist becomes, the stronger I become as a heart demon. Moreover, as long as I win every battle and avoid being slain by the protagonist, I can continue growing stronger. As the saying goes, “Cultivate to become an immortal, slay the heart demon, and perfect the true self.” But I, Su Lin, am the heart demon they will never be able to slay! Huang: “I feel as if I have lived my entire life beneath his shadow!” Xiao: “Why is my heart demon stronger than me, with a firmer Dao heart than mine, and even faster at spinning fire lotuses than I am? Who exactly is the heart demon here?” Hongjun: “Slay the Three Corpses and merge with the Dao. Wait, that's not right?! Why is there one corpse I can't slay!” One day, the Myriad Worlds merged, and the children of destiny from the various planes emerged to compete for the final Dao Fruit. When they looked up, they discovered that Su Lin was already standing atop the Dao Fruit, having achieved the supreme Dao position! Only then did the children of destiny realize that throughout their entire lives, they had never escaped the shadow of Su Lin's domination!