Prescription: Madness

What does it feel like to be a sentient body part that's attached to another being?

Welcome to the Netherworld, where you play as a sentient tentacle of the great master Cthulhu. What happens when a sentient tentacle, wants to find its own purpose? Like get a job? Or rid the world of humanity? Or play doctor at hospital in the Overworld? How would that... work?