11 letters inside (1996)

This is a story about a man who believes that he has two “selves” - external and internal. That is, an organism is a certain conglomerate of cells, each of which is a separate individual. This hybrid creature has a certain common personal “I” that uses the entire organism, and is the organism itself, which has its own will. According to the character, one can communicate with him, which is what he is trying to do. He wants to reach him and comes up with different ways of communication: injecting substances under the skin or intravenously, tattooing texts on the body, swallowing objects. The answer would come in the form of a rash or other physical manifestation that had to be interpreted. As a result, communication is carried out and the second “I” agrees to die.