Forty years recorded in alien paint
In 'Spectrum' a human scientist is stranded on an unknown planet and lives for about forty years among beings who perceive and communicate through colour rather than sound. One of them keeps her alive and records her life in painted colour sequences. When that individual dies, a successor takes on the same name and learns their shared history by reading the paintings, so her companion is really a chain of beings carried forward by a colour archive. Back on Earth her account of this relationship is treated as unverifiable, and that question of proof frames the story.