The Parasite

Olivia and her twin have shared one body since before birth, and they have been enemies from the very start. Olivia calls her sister the parasite, the monster who ruined her life. When the narrator finds a hidden medical file in the attic, a faded sonogram and a doctor's notes reveal a single healthy baby girl named Olivia, and a rare parasitic twin that appeared months later. Everything Olivia ever said was true.

At dinner, Olivia refuses every spoonful, trying to starve the parasite out of their shared stomach. The narrator retaliates with lemon juice, and Olivia finally eats, cursing her between mouthfuls. Later, Olivia forces her own heart medication down her sister's throat, taking a double dose herself and refusing her own pills, determined that they die together. As Olivia's heart fails and the poison spreads through their shared body, the narrator screams for their mother.

A doctor tells their mother that the case is incredibly complex, and that with current medical technology, only one of them could be saved.