Hypothetical: The parasitic twin

Jake lives in an alternate universe where sun-damage can cause a parasitic twin to start forming on your skin. Jake has been spending a lot of time in the sun, because he loves getting a tan, and a rather large growth has formed on his back without anyone bothering to tell him. When he finally notices it, he goes to a clinic that purports to offer dermatological services, but it turns out it’s a “Every mole is sacred”-type place and the advisor there, who wears a white coat and a stethoscope, but isn’t a doctor, tells Jake that the pulsation of the growth is a heartbeat, that he’s named the growth Blake, and that Blake really, really wants to live. In fact, the advisor was himself a growth that was allowed to grow until he could be separated and live independently.

Which of the two should have the final say in the matter? Jake the sun-lover, or the mole only the fake doctor considers to be “Blake”?